ans

#include <bits/stdc++.h>
#define int long long
using namespace std;
int w[3000011], c[3000011];
signed main() {
    int n, m, ans = 0, j = 1;
    cin >> n >> m;
    for (int i = 1; i <= n; i++) cin >> w[i];//钱
    for (int i = 1; i <= m; i++) cin >> c[i];//价格
    sort(w + 1, w + 1 + n);
    sort(c + 1, c + 1 + m);
    for (int i = 1; i <= m; i++) {
        if (j > n)
            break;
        while (1) {
            if (w[j] < c[i])
                j++;
            else {
                ans++;
                break;
            }
        }
        j++;
    }
    cout << ans;
    return 0;
}