#include <bits/stdc++.h>

using namespace std;

#define REP(i,a,b) for(int i=a;i<b;i++)
#define rep(i,n) REP(i,0,n)

bool dp[10110];

int main() {
  int N; cin >> N;
  int sum = 0;
  int W[N]; rep(i, N) { cin >> W[i]; sum += W[i]; }
  dp[0] = 1;
  if(sum & 1) goto FAIL;
  rep(i, 10000) rep(j, N)
    if(dp[i]) { dp[i+W[j]] = 1; }
  
  if(dp[sum/2]) {
    cout << "possible\n";
    return 0;
  }
  
 FAIL:;
  cout << "impossible\n";
  return 0;
}