#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+6;
long long n,nn,a[N];
int main(){
	scanf("%lld%lld",&n,&nn);
	for (int i = 1;i <= nn;++i){
		scanf("%lld",&a[i]);
	}
	sort(a,a+nn);
	int ans=0;
	int sum=1;
	for (int i = nn;i >= 1;--i){
		int flag=a[sum]+a[i];
		int p=0;
		for (int j = 1;j <= nn;++j){
			if (a[j] == -1){
				p++;
			}
		}
		if (p >= nn){
			break;
		}
		if (flag <= n){
			a[sum]=-1;a[i]=-1;
			ans++;sum++;
		}else{
			a[i]=-1;
			ans++;
		}
	}
	printf("%d",ans);
	return 0;
}