#include <bits/stdc++.h>
//#define int long long
#define double long double
#define Task "MAXLEN"
#define READFILE freopen(Task".inp", "r", stdin)
#define WRITEFILE freopen(Task".out", "w", stdout)
#define double long double
#define oo 0x3f3f3f3f3f
#define FAST ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL)
#define mp make_pair
#define pb push_back
#define X first
#define Y second
#define watch(x) cout << (#x) << " = " << x << endl
#define debug(x) cout << (#x) << " = " << x << endl
#define all(x) x.begin(), x.end()
#define sz(x) x.size()
#define endl '\n'
#define max3(a,b,c) max(max(a, b), c)
#define max4(a,b,c,d) max(max(a, b), max(c, d))
#define min4(a,b,c,d) min(min(a, b), min(c, d))
#define debug4(a,b,c,d) watch(a);watch(b);watch(c);watch(d)
#define ever (;true;)
#define maxn 505

#define PI 3.14159265

using namespace std;

typedef pair < int, int > ii;
typedef pair < int, ii > iii;
typedef pair < ii, ii > iiii;
typedef vector < int > vi;
typedef vector < ii > vii;
typedef vector < vi > vvi;
typedef vector < iii > viii;
typedef vector < vii > vvii;
typedef vector < iiii > viiii;
typedef vector < vvi > vvvi;

const int N = 1e5 + 5;
const int Blocksize = 316;

int n, q;
int a[N];

int b[Blocksize + 5][N];
int c[Blocksize + 5][N];

struct Nho{
    int nho[N];
    int TimeUpdate[N];
    int Time = 0;
    Nho(){
        memset(TimeUpdate, 0, sizeof(TimeUpdate));
        Time = 1;
    }

    void set(int i, int val){
        TimeUpdate[i] = Time;
        nho[i] = val;
    }

    int Get(int i){
        if (TimeUpdate[i] != Time) return 0;
        return nho[i];
    }

    void reset(){
        ++Time;
    }

}nho;

void init(){
    FAST;
    #ifndef ONLINE_JUDGE
    READFILE;
    WRITEFILE;
    #endif // ONLINE_JUDGE
    scanf("%d%d", &n, &q);
    for (int i = 1; i <= n; ++i){
        scanf("%d", a + i);
    }
    vi val(a+1, a+1+n);
    sort(all(val));
    for (int i = 1; i <= n; ++i){
        a[i] = lower_bound(all(val), a[i]) - val.begin();
    }
}

void pp(){
    for (int k = 0; (k+1) * Blocksize <= n; ++k){
        nho.reset();
        for (int i = k*Blocksize + 1; i <= n; ++i){
            int j = nho.Get(a[i]);
            b[k][i] = b[k][i-1];
            if (j) b[k][i] = max(b[k][i], i - j);
            else nho.set(a[i], i);
        }
    }
    for (int k = 0; (k+1) * Blocksize <= n; ++k){
        nho.reset();
        for (int i = (k+1) * Blocksize; i >= 1; --i){
            int j = nho.Get(a[i]);
            c[k][i] = c[k][i+1];
            if (j) c[k][i] = max(c[k][i], j - i);
            else nho.set(a[i], i);
        }
    }
}

void Solve(){
    while (q--){
        int l, r;
        scanf("%d%d", &l, &r);
        int u = (l - 1) / Blocksize;
        int v = (r - 1) / Blocksize;
        if (v - u <= 1){
            nho.reset();
            int ans = 0;
            for (int i = l; i <= r; ++i){
                int j = nho.Get(a[i]);
                if (j) ans = max(ans, i - j);
                else nho.set(a[i], i);
            }
            cout << ans << endl;
        }
        else{
            int ans = max(b[u+1][r], c[v-1][l]);
            nho.reset();
            for (int i = l; i <= (u+1) * Blocksize; ++i){
                int j = nho.Get(a[i]);
                if (j) ans = max(ans, i - j);
                else nho.set(a[i], i);
            }
            for (int i = v*Blocksize + 1; i <= r; ++i){
                int j = nho.Get(a[i]);
                if (j) ans = max(ans, i - j);
                else nho.set(a[i], i);
            }
            cout << ans << endl;
        }
    }
}

signed main(){
    init();
    pp();
    Solve();
    return 0;
}