#include<iostream>
#include<algorithm>
const int N = 3e4 + 10;
#define long long int;
using namespace std;    
int main(){
    int w;
    cin >> w;
    int n;
    int a[N];
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> a[i];
    }
    sort(a, a + n);
    int l = 0, r = n-1,t=0;
    while (l < r) {

        while (a[l] + a[r] > w) r--;
        l++,r--,t++;

    }
    int ans = t + n - 2 * t;
    cout << ans << endl;




    return 0;

    }