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

const string msg[] = { "impossible", "possible" };

signed main(){
  int N; cin >> N;
  vector< int > W( N );
  for( int i = 0; i < N; ++i )
    cin >> W[ i ];
  int maxw = *max_element( W.begin(), W.end() );
  int maxws = maxw * N;
  vector< vector< int > > dp( N + 1, vector< int >( 2 * ( maxws + 1 ) ) );
  dp[ 0 ][ maxws ] = 1;
  for( int i = 0; i < N; ++i )
    for( int j = 0; j <= 2 * maxws; ++j ){
      if( j + W[ i ] <= 2 * maxws )
        dp[ i + 1 ][ j + W[ i ] ] |= dp[ i ][ j ];
      if( 0 <= j - W[ i ] )
        dp[ i + 1 ][ j - W[ i ] ] |= dp[ i ][ j ];
    }
  cout << msg[ dp[ N ][ maxws ] ] << endl;
  return 0;
}