#include <bits/stdc++.h>
using namespace std;
const int N=30010;
int n,m;
int w[N];

int main() {
    cin>>m>>n;
    for (int i = 0; i < n; i++) cin >> w[i];
    sort(w, w + n);
    int res = 0;
     for (int i = 0, j = n - 1; i <= j; j--) {
        if (w[i] + w[j] <= m) i++;
        res++;
    }
    cout << res << endl;
    return 0;
}