#include<bits/stdc++.h>
#define MOD 1000000007
#define INF 0x3f3f3f3f
#define INFL 0x3f3f3f3f3f3f3f3f
#define EPS (1e-10)
#define rep(i,n)for(int i=0;i<n;i++)
using namespace std;
typedef long long ll;
typedef pair<int, int>P;

bool dp[101][30000];
int d[100];
int main() {
	int n; scanf("%d", &n);
	rep(i, n)scanf("%d", &d[i]);
	dp[0][15000] = 1;
	rep(i, n) {
		rep(j, 30000) {
			if (j + d[i] < 30000)dp[i + 1][j + d[i]] |= dp[i][j];
			if (j - d[i] >= 0)dp[i + 1][j - d[i]] |= dp[i][j];
		}
	}
	puts(dp[n][15000] ? "possible" : "impossible");
}