#include <numeric>
#define REP(i,n) for(int i=0; i<(int)(n); i++)

#include <queue>
#include <cstdio>
inline int getInt(){ int s; scanf("%d", &s); return s; }

#include <set>

using namespace std;

int main(){
  const int n = getInt();
  vector<int> w(n);
  REP(i,n) w[i] = getInt();
  const int mx = accumulate(w.begin(), w.end(), 0);

  vector<int> dp(mx + 1);
  dp[0] = 1;
  REP(i,n){
    for(int j = mx; j >= 0; j--){
      if(dp[j]) dp[j + w[i]] = 1;
    }
  }

  puts(mx % 2 == 0 && dp[mx / 2] ? "possible" : "impossible");

  return 0;
}