#include <iostream>
#include <algorithm>
using namespace std;
int main(){
    int n,m;
	int a[30001];
    cin >> m >> n;
    for (int i = 0;i<n;i++){
        cin>>a[i];
    }
    
    sort(a+1,a+n+1);
    int b=1;
	int s=0;
    for(int i=n;i>=b;i--){
        for(int j=b;j<=i;j++){
            if(a[i]+a[j]>m){
                s++;
                break;
            }
            if(a[i]+a[j]<=m){
                b++;
                s++;
                break;
            }
        }
    }
    cout<<s;
    return 0;
}