#include<bits/stdc++.h>
using namespace std;
int w,n,a[300005],sum;
int main(){
    freopen("kaj.in","r",stdin);
    freopen("kaj.out","w",stdout);
    cin>>w>>n;
    for(int i=1;i<=n;i++){
        cin>>a[i];
    }
    sort(a+1,a+n+1);
    int i=1,j=n;
    while(i<=j){
        if(i==j){
            sum++;
            break;
        }
        if(w>=a[i]+a[j]){
            i++;
            j--;
        }
        else{
            j--;
        }
        sum++;
    }
    cout<<sum;
    return 0;
}