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

int N;
vector<int> W(110);
bool memo[110][10009];

int main(){
  cin >> N;
  int sum=0;
  for(int i=1;i<=N;i++){cin >> W[i]; sum+=W[i];}
  if(sum%2==1){cout << "impossible" << endl; return 0;}
  int n=sum/2;
  memo[0][0]=1;
  for(int i=1;i<=N;i++){
    for(int j=0;j<=n;j++){
      memo[i][j]|=memo[i-1][j];
      if(j-W[i]>=0){memo[i][j]|=memo[i-1][j-W[i]];}
    }
  }
  if(memo[N][n]){cout << "possible" << endl;}
  else{cout << "impossible" << endl;}
}