#include <iostream>
#include <cstdio>
#include <cmath>
#include <vector>
#include <deque>
#include <list>
#include <string>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>

using namespace std;

bool dp[101][5010];

int N;
int W[101];
int sum;

bool check(int num, int psum) {
	int i;
	bool flag = false;

	if (psum == sum/2) return true;
	if (psum > sum/2) return false;
	if (num == N) return false;

	for (i = 0; i <= num; i++) {
		flag = flag || dp[i][psum];
	}
	if (flag) return false;

	flag = check(num+1, psum) || check(num+1, psum+W[num]);

	dp[num][psum] = !flag;

	return flag;
}

int main() {
	int i;

	cin >> N;

	sum = 0;
	for (i = 0; i < N; i++) {
		cin >> W[i];
		sum += W[i];
	}
	
	if (sum % 2) {
		cout << "impossible" << endl;
		return 0;
	}

	bool flag = check(0, 0);

	if (flag) cout << "possible" << endl;
	else cout << "impossible" << endl;

	return 0;
}