/*
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      MIPTCLASSICMIPTCLASSICMIPTCLASSICMIPTCLASSICMIPTCLASSICMIPTCLASSIC
*/

// #define pragma

#ifdef pragma
#pragma GCC optimize("Ofast")
#pragma GCC optimize("no-stack-protector")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#pragma GCC optimize("unroll-loops")
#pragma GCC diagnostic ignored "-Wunused-result"
#endif // pragma

#include<bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>

#define ll long long
#define all(x) begin(x), end(x)
#define pb push_back
#define x first
#define y second
#define int long long
#define zero(two) memset(two, 0, sizeof(two))

using namespace std;
using namespace __gnu_pbds;


typedef vector<int> vi;
typedef vector<bool> vb;
typedef pair<int, int> pii;
typedef long double ld;
typedef vector<vi> matrix;
template<typename T>
using kawaii_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;

const ld PI = atan2(0, -1);

void seriy() {
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    cout << fixed << setprecision(10);
    #if 0
        freopen("input", "r", stdin);
        freopen("output", "w", stdout);
    #endif
}

/** Fast input-output */

template <class T = int> inline T readInt();
inline double readDouble();
inline int readUInt();
inline int readChar(); // first non-blank character
inline void readWord( char *s );
inline bool readLine( char *s ); // do not save '\n'
inline bool isEof();
inline int getChar();
inline int peekChar();
inline bool seekEof();
inline void skipBlanks();

template <class T> inline void writeInt( T x, char end = 0, int len = -1 );
inline void writeChar( int x );
inline void writeWord( const char *s );
inline void writeDouble( double x, int len = 0 );
inline void flush();

static struct buffer_flusher_t {
    ~buffer_flusher_t() {
        flush();
    }
} buffer_flusher;

/** Read */

static const int buf_size = 4096;

static unsigned char buf[buf_size];
static int buf_len = 0, buf_pos = 0;

inline bool isEof() {
    if (buf_pos == buf_len) {
        buf_pos = 0, buf_len = fread(buf, 1, buf_size, stdin);
        if (buf_pos == buf_len)
            return 1;
    }
    return 0;
}


inline int getChar() {
    return isEof() ? -1 : buf[buf_pos++];
}

inline int peekChar() {
    return isEof() ? -1 : buf[buf_pos];
}

inline bool seekEof() {
    int c;
    while ((c = peekChar()) != -1 && c <= 32)
        buf_pos++;
    return c == -1;
}

inline void skipBlanks() {
    while (!isEof() && buf[buf_pos] <= 32U)
        buf_pos++;
}

inline int readChar() {
    int c = getChar();
    while (c != -1 && c <= 32)
        c = getChar();
    return c;
}

inline int readUInt() {
    int c = readChar(), x = 0;
    while ('0' <= c && c <= '9')
        x = x * 10 + c - '0', c = getChar();
    return x;
}

template <class T>
inline T readInt() {
    int s = 1, c = readChar();
    T x = 0;
    if (c == '-')
        s = -1, c = getChar();
    else if (c == '+')
        c = getChar();
    while ('0' <= c && c <= '9')
        x = x * 10 + c - '0', c = getChar();
    return s == 1 ? x : -x;
}

inline double readDouble() {
    int s = 1, c = readChar();
    double x = 0;
    if (c == '-')
        s = -1, c = getChar();
    while ('0' <= c && c <= '9')
        x = x * 10 + c - '0', c = getChar();
    if (c == '.') {
        c = getChar();
        double coef = 1;
        while ('0' <= c && c <= '9')
            x += (c - '0') * (coef *= 1e-1), c = getChar();
    }
    return s == 1 ? x : -x;
}

inline void readWord( char *s ) {
    int c = readChar();
    while (c > 32)
        *s++ = c, c = getChar();
    *s = 0;
}

inline bool readLine( char *s ) {
    int c = getChar();
    while (c != '\n' && c != -1)
        *s++ = c, c = getChar();
    *s = 0;
    return c != -1;
}

/** Write */

static int write_buf_pos = 0;
static char write_buf[buf_size];

inline void writeChar( int x ) {
    if (write_buf_pos == buf_size)
        fwrite(write_buf, 1, buf_size, stdout), write_buf_pos = 0;
    write_buf[write_buf_pos++] = x;
}

inline void flush() {
    if (write_buf_pos)
        fwrite(write_buf, 1, write_buf_pos, stdout), write_buf_pos = 0;
}

template <class T>
inline void writeInt( T x, char end, int output_len ) {
    if (x < 0)
        writeChar('-'), x = -x;

    char s[24];
    int n = 0;
    while (x || !n)
        s[n++] = '0' + x % 10, x /= 10;
    while (n < output_len)
        s[n++] = '0';
    while (n--)
        writeChar(s[n]);
    if (end)
        writeChar(end);
}

inline void writeWord( const char *s ) {
    while (*s)
        writeChar(*s++);
}

inline void writeDouble( double x, int output_len ) {
    if (x < 0)
        writeChar('-'), x = -x;
    int t = (int)x;
    writeInt(t), x -= t;
    writeChar('.');
    for (int i = output_len - 1; i > 0; i--) {
        x *= 10;
        t = std::min(9ll, (int)x);
        writeChar('0' + t), x -= t;
    }
    x *= 10;
    t = std::min(9ll, (int)(x + 0.5));
    writeChar('0' + t);
}

struct rrq {
    int t, l, r, id;
};

struct crq {
    int t, pos, val;
};

const int INF = 1e9 + 7;
const int MAXN = 1e6 + 100;

int k, kt;
vi addpos;
matrix add;
vi a, ccc(MAXN);
int curpos = 0;
vector<crq> crqs;
int curl = 1, curr = 0, curt = 0;

bool cmp(rrq a, rrq b) {
    if(a.t / kt != b.t / kt) {
        return a.t < b.t;
    }
    else if(a.l / k != b.l / k) {
        return a.l < b.l;
    }
    return a.r < b.r;
}

void addLeft(int pos) {
    pos = a[pos];
    ccc[pos]++;
    if(pos == curpos) {
        while(ccc[curpos]) {
            curpos++;
        }
    }
}

void addRight(int pos) {
    addLeft(pos);
}

void delLeft(int pos) {
    pos = a[pos];
    ccc[pos]--;
    if(ccc[pos] == 0 && pos < curpos) {
        curpos = pos;
    }
}

void delRight(int pos) {
    delLeft(pos);
}

void addT(int num) {
    int pos = crqs[num].pos;
    int val = crqs[num].val;
    if(pos >= curl && pos <= curr) {
        delLeft(pos);
    }
    addpos[pos]++;
    a[pos] = val;
    if(pos >= curl && pos <= curr) {
        addLeft(pos);
    }
}

void delT(int num) {
    int pos = crqs[num].pos;
    if(pos >= curl && pos <= curr) {
        ccc[a[pos]]--;
        if(ccc[a[pos]] == 0 && a[pos] < curpos) {
            curpos = a[pos];
        }
    }
    addpos[pos]--;
    a[pos] = add[pos][addpos[pos]];
    if(pos >= curl && pos <= curr) {
        addLeft(pos);
    }
}

int answer() {
    return curpos;
}

signed main() {
    seriy();
    int n, q;
    n = readInt();
    q = readInt();
    a.resize(n);
    add.resize(n);
    addpos.resize(n, 0);
    for(int i = 0; i < n; i++) {
        a[i] = readInt();
        add[i].pb(a[i]);
    }
    vi l(q), r(q);
    int tt = 0;
    vector<rrq> rqs;

    for(int i = 0; i < q; i++) {
        char rq;
        rq = readChar();
        l[i] = readInt();
        r[i] = readInt();
        l[i]--;
        if(rq == '!') {
            crqs.pb({tt + 1, l[i], r[i]});
            add[l[i]].pb(r[i]);
//            cerr << l[i] << " " << r[i] << '\n';
            tt++;
        }
        else {
            r[i]--;
            rqs.pb({tt, l[i], r[i], i});
        }
    }
    int num = 0;
    k = pow(n, 2. / 3.);
    kt = pow(tt, 2. / 3.) + 1;
    sort(all(rqs), cmp);
    vi ans(q, -1);
    for(int i = 0; i < rqs.size(); i++) {
        while(curl > rqs[i].l) {
            curl--;
            addLeft(curl);
        }
        while(curr < rqs[i].r) {
            curr++;
            addRight(curr);
        }

        while(curl < rqs[i].l) {
            delLeft(curl);
            curl++;
        }
        while(curr > rqs[i].r) {
            delRight(curr);
            curr--;
        }
        while(curt < rqs[i].t) {
            addT(curt);
            curt++;
        }
        while(curt > rqs[i].t) {
            curt--;
            delT(curt);
        }
//        for(auto j : a) {
//            cerr << j << " ";
//        }
//        cerr << '\n';
//        cerr << rqs[i].t << " " << rqs[i].l << " " << rqs[i].r << " " << answer() << '\n';
        ans[rqs[i].id] = answer();
    }
    for(auto i : ans) {
        if(i != -1) {
            writeInt(i);
            writeChar('\n');
        }
    }
    return 0;
}