#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for (int i = 0; i < n; ++i)
using ll = long long;
const int SIZE=10000;
bool dp[SIZE+1];
int main() {
   int N;cin>>N;
   int sum=0;
   dp[0]=true;
   rep(i,N){
      int wi;cin>>wi;
      sum+=wi;
      for (int i = SIZE; i >= 0; i--)
      {
         if(i+wi>SIZE)continue;
         if(dp[i])dp[i+wi]=true;
      }
   }
   if(sum%2==1)cout<<"impossible"<<endl;
   else {
      if(dp[sum/2])cout<<"possible"<<endl;
      else cout<<"impossible"<<endl;
   }
}