#include <bits/stdc++.h>
using namespace std;

#define ll long long
#define pb push_back
#define mp make_pair
#define fi first
#define se second

const int inf = 1e9 + 7;

void solve() {
    int n, m;
    cin >> n >> m;
    vector<int> a(1 + n, 0);
    vector<int> b(1 + m, 0);
    for(int i = 1; i <= n; i++) {
        cin >> a[i];
    }
    for(int i = 1; i <= m; i++) {
        cin >> b[i];
    }
    sort(b.begin() + 1, b.end());
    vector<int> req(1 + n, inf);
    // req[i]: minimum hany valtoztatas kell mindenkepp (az elso i elemen ertelmezve)
    vector<vector<int> > dp(1 + n, vector<int> (1 + n, inf));
    // dp[i][j]: max j darab valtoztatassal mi a legkisebb maximum (az elso i elemen ertelmezve)
    // dp[i] csokkeno
    for(int j = 0; j <= n; j++) {
        dp[0][j] = 0;
    }
    req[0] = 0;
    for(int i = 1; i <= n; i++) {
        for(int j = req[i - 1]; j <= n; j++) {
            if(dp[i - 1][j] < a[i]) {
                dp[i][j] = a[i];
            }
        }
        for(int j = req[i - 1]; j < n; j++) {
            auto it = upper_bound(b.begin(), b.end(), dp[i - 1][j]);
            if(it == b.end()) {
                continue;
            }
            int num = *it;
            dp[i][j + 1] = min(dp[i][j + 1], num);
        }
        for(int j = 0; j <= n; j++) {
            if(dp[i][j] != inf) {
                req[i] = j;
                break;
            }
        }
    }
    cout << req[n] << "\n";
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(nullptr);
    solve();
    return 0;
}