#include <bits/stdc++.h>

using namespace std;

#define REP(i,first,last) for (int i=first;i<last;i++)
#define MAX(x,y) (x > y ? x : y)
#define MIN(x,y) (x < y ? x : y)
#define prints(str) cout << str << " ";
#define printn(str) cout << str << endl;

int main(){
  int N;
  cin >> N;
  vector<int> w_list(N);
  bitset<10001> dp;

  int total = 0;
  REP(i,0,N){
    cin >> w_list[i];
    total += w_list[i];
  }

  if (total & 1 == 1) {
    printn("impossible");
    return 0;
  }

  int half = total >> 1;
  dp[0] = 1;

  for (auto w: w_list) {
    dp |= dp << w;
    if (dp[half]) {
      printn("possible");
      return 0;
    }
  }

  printn("impossible");
}