#include<bits/stdc++.h>
using namespace std;

int n;
int data[111];
int memo[111][11111];

bool solve(int p, int w){

  if(p == n && w == 11111) return true;
  if(p == n) return false;
  if(~memo[p][w]) return memo[p][w];
  
  int ret = false;
  ret |= solve(p+1, w+data[p]) | solve(p+1, w-data[p]);

  return memo[p][w] = ret;
}

int main(){

  cin >> n;
  for(int i=0;i<n;i++) cin >> data[i];

  memset(memo, -1, sizeof(memo));
  if(solve(0, 11111)) puts("possible");
  else puts("impossible");

}