#include<bits/stdc++.h>
#define int long long
const int N = 1e5;
using namespace std;
int n,m;
int c[N],w[N];
int f[N];
int ans = 0;
signed main() {
	freopen("mushro.in","r",stdin);
	freopen("mushro.out","w",stdout);
	cin >> n >> m;
	for (int i = 1; i <= n; ++i) cin >> c[i];
	for (int i = 1; i <= m; ++i) cin >> w[i];
	sort (w+1,w+1+m);
	sort (c+1,c+1+n);
	for (int i = 1; i <= m; ++i) {
		for (int j = 1; j <= n; ++j) {
			if (c[j] >= w[i]) {
				c[j] -= w[i];
				ans++;
				sort(c+1,c+1+n);
				break;
			}
		}
	}
	cout << ans;
	return 0;
}