easy

#include<bits/stdc++.h>
using namespace std;
int a[30005];
bool cmp(const int a,const int b){return a < b;}
int main(){
    int m,n; cin >> m >> n;
    for(int i = 1;i <= n;i++) cin >> a[i];
    sort(a + 1,a + n + 1,cmp);
    int ans = 0;
    int l = 1,r = n;
    while(l <= r){
        if(a[l] + a[r] <= m){
            ans++;
            l++;
            r--;
        }else{
            ans++;
            r--;
        }
    }
    cout << ans;
    return 0;
}