#include <vector>
#include <algorithm>
#include <cstdio>
using namespace std;
#define Z(C,D,P)for(R=0,lo=0,hi=N-1;lo<hi;C){for(;lo<hi;D)if(v[lo]+v[hi] P 0)break;if(lo==hi)break;};printf("%d ",R);
int main(){
	int N,R,lo,hi;
	scanf("%d",&N);
	vector<int>v(N*=2);
	for(int i=0;i<N;i++)scanf("%d",&v[i]);
	sort(v.begin(),v.end());
	Z(R++|lo++|hi--,hi--,<)Z(R++|lo++|hi--,lo++,>)Z((v[lo]+v[hi]==0?R++|hi--:1,lo++),hi--,<=)
}