#include <iostream>
using namespace std;

#define MAXW 10002

bool dp[MAXW];

int main(){
   dp[0] = true;
   int sum = 0,n;
   cin >> n;
   int w[n];
   for(int i = 0;i < n;i++){
      cin >> w[i];
      sum += w[i];
   }
   for(int i = 0;i < n;i++) for(int j = MAXW - 1 - w[i];j >= 0;j--) dp[j + w[i]] |= dp[j];
   cout << (sum & 1 || !dp[sum / 2] ? "impossible" : "possible") << endl;
}