#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstring>
#include <cmath>
#include <vector>
#include <list>
#include <string>
#include <set>
#include <map>
#include <queue>
#include <stack>
#include <algorithm>
#include <iostream>
#include <sstream>
using namespace std;
typedef long long int llint;
const int INF = 1000000;
const llint LINF = 100000000;
int n, num[100000];
int dp[10000][10000];
int dfs(int i,int sum1, int sum2) {
	if (i == n) { return sum1 == sum2; }
	else if (dp[sum1][sum2] > 0) {
		return dp[sum1][sum2];
	}
	else {
		 
		if (dfs(i + 1, sum1 + num[i], sum2))return dp[sum1][sum2] = dp[sum2][sum1] =  1;
		if (dfs(i + 1, sum1, sum2 + num[i])) return dp[sum1][sum2] = dp[sum2][sum1] = 1;
		return false;
	}
}
int main() {
	cin >> n;
	for (int i = 0; i < n; i++) { cin >> num[i]; }
	if (dfs(0, 0, 0))cout << "possible\n";
	else cout << "inpossible\n";

	return 0;




}