#include"bits/stdc++.h"
//#include<bits/stdc++.h>
using namespace std;
#define print(x) cout<<x<<endl;
#define rep(i,a,b) for(int i=a;i<b;i++)
typedef long long ll;
//const int mod = 1e9 + 7;

int n;
int w[102];
int sum = 0;
int half = 0;
int dp[102][10000];

int solve(int i, int sum) {
	if (dp[i][sum] != -1)return dp[i][sum];
	if (i == n&&sum == half) { return dp[i][sum] = 1; }
	if (solve(i + 1, sum)) { return dp[i+1][sum] = 1; }
	if (solve(i + 1, sum + w[i])) { return dp[i+1][sum+w[i]] = 1; }
	return dp[i][sum] = 0;
}

int main() {
	cin >> n;
	rep(i, 0, n) { cin >> w[i]; half += w[i]; }
	if (half % 2 == 1) {
		print("impossible"); return 0;
	}
	half /= 2;
	memset(dp, -1, sizeof(dp));
	if (solve(0, 0)) { print("possible"); }
	else { print("impossible"); return 0; }
	return 0;
}