#include <algorithm>
#include <cstdio>
#include <iostream>
#include <map>
#include <math.h>
#include <queue>
#include <set>
#include <sstream>
#include <stack>
#include <string>
#include <vector>
using namespace std;

#define ll long long
#define INF (1 << 30)
#define INFLL (1LL << 60)

int n,w[101],make_num;

bool bfs(int now,int sum){
	if(sum == make_num) return true;
	if(sum > make_num || now == -1) return false;

	return bfs(now - 1,sum + w[now]) || bfs(now - 1,sum);
}

int main() {
	bool ans = false;
	cin >> n;
	for(int i = 0;i < n;i++){
		cin >> w[i];
		make_num += w[i];
	}
	sort(w,w + n);
	if(make_num % 2 == 1) ans = false;
	else{
		make_num = make_num / 2;
		ans = bfs(n-1,0);
	}

	if(ans) cout << "possible" << endl;
	else cout << "impossible" << endl;
	return 0;
}