#include <bits/stdc++.h> 

using namespace std;

int main() {
    int L, N; cin >> L >> N;
    vector<int> W(N);
    for (int i = 0; i < N; i++) { cin >> W[i]; }
    sort(begin(W), end(W));
    
    int sum = 0;
    int ans = -1;
    for (int i = 0; i < N; i++) {
        if (sum + W[i] <= L) {
            sum += W[i];
        } else {
            ans = i;
            break;
        }
    }
    cout << ans << endl;
}