#include<bits/stdc++.h>

using namespace std;

using ll = long long;
using ld = long double;
using ull = unsigned long long;

using pii = pair<int, int>;
using pll = pair<ll, ll>;
using pld = pair<ld, ld>;

#define fi first
#define se second
#define pb push_back
#define pf push_front
#define mp make_pair
#define ins insert
#define btpc __builtin_popcount
#define btclz __builtin_clz

#define sz(x) (int)(x.size());
#define all(x) x.begin(), x.end()
#define debug(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

int d4x[4] = {1, 0, -1, 0}; int d4y[4] = {0, 1, 0, -1};
int d8x[8] = {0, 1, 1, 1, 0, -1, -1, -1};
int d8y[8] = {1, 1, 0, -1, -1, -1, 0, 1};

template<class X, class Y>
    bool minimize(X &x, const Y &y) {
        if (x > y)
        {
            x = y;
            return true;
        }
        return false;
    }
template<class X, class Y>
    bool maximize(X &x, const Y &y) {
        if (x < y)
        {
            x = y;
            return true;
        }
        return false;
    }

const int MOD = 1e9 + 7; //998244353

template<class X, class Y>
    void add(X &x, const Y &y) {
        x = (x + y);
        if(x >= MOD) x -= MOD;
    }

template<class X, class Y>
    void sub(X &x, const Y &y) {
        x = (x - y);
        if(x < 0) x += MOD;
    }

/* Author : Le Ngoc Bao Anh, 12A5, LQD High School for Gifted Student*/

const ll INF = 1e9;
const int N = 2000 + 10;

template <class T> struct FenwickTree {
    int n;
    vector<T> bit;

    FenwickTree(int _n = 0) {
        n = _n;
        bit.resize(n + 5);
        for(int i = 1; i <= n; i++) bit[i] = 0;
    }

    void update(int pos, T x) {
        for(int i = pos; i <= n; i += i & (-i)) maximize(bit[i], x);
    }

    T get(int pos) {
        T ans = 0;
        for(int i = pos; i > 0; i -= i & (-i)) maximize(ans, bit[i]);
        return ans;
    }
};

int a[N], b[N], f[N][N];
FenwickTree<int> pref[N], suff[N];
int nxt[N][25];

void solve() {
    int n, m; cin >> n >> m;
    for(int i = 1; i <= n; i++) cin >> b[i];
    vector<int> val;
    for(int i = 1; i <= m; i++) {
        cin >> a[i];
        val.pb(a[i]);
    }

    sort(all(val)); val.resize(unique(all(val)) - val.begin());

    for(int i = 1; i <= m; i++) {
        a[i] = lower_bound(all(val), a[i]) - val.begin() + 1;
    }

    // f[x][j] -> f[x][pos]
    // f[i ; i < x][j] -> f[x][pos]
    // f[i; i > x][j] -> f[x][pos];

    swap(n, m);
    for(int i = 1; i <= m; i++) {
        pref[i] = FenwickTree<int>(n);
        suff[i] = FenwickTree<int>(n);
    }

    for(int j = 1; j <= m; j++) {
        pref[j].update(a[1], 1);
        suff[j].update(n - a[1] + 1, 1);
    }

    for(int i = 1; i <= 20; i++) nxt[m + 1][i] = INF;
    for(int i = m; i >= 1; i--) {
        for(int j = 1; j <= 20; j++) nxt[i][j] = nxt[i + 1][j];
        nxt[i][b[i]] = i;
    }

    for(int i = 2; i <= n; i++) {
        for(int j = m; j >= 1; j--) {
            int v = f[a[i]][j];
            int pos = nxt[j + 1][b[j]];
            if(pos < INF) {
                maximize(f[a[i]][pos], v + 1);
                pref[pos].update(a[i], v + 1);
                suff[pos].update(n - a[i] + 1, v + 1);
            }
        }

        FenwickTree<int> p, s;
        p = s = FenwickTree<int>(21);

        for(int j = 1; j <= m; j++) {
            maximize(f[a[i]][j], p.get(b[j] - 1) + 1);
            maximize(f[a[i]][j], s.get(20 - b[j]) + 1);
            p.update(b[j], pref[j].get(a[i] - 1));
            s.update(20 - b[j] + 1, suff[j].get(n - a[i]));
            pref[j].update(a[i], f[a[i]][j]);
            suff[j].update(n - a[i] + 1, f[a[i]][j]);
        }
    }

    int ans = 0;
    for(int i = 1; i <= m; i++) maximize(ans, pref[i].get(n));
    cout << n + m - 2 * ans;
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    #ifndef ONLINE_JUDGE
    freopen("input.txt", "r", stdin);
    freopen("output.txt", "w", stdout);
    #else
    //online
    #endif

    int tc = 1, ddd = 0;
    // cin >> tc;
    while(tc--) {
        //ddd++;
        //cout << "Case #" << ddd << ": ";
        solve();
    }
}