#include <cstdio>
#define repi(i,a,b) for(int i=(a);i<(b);++i)
#define rep(i,a) repi(i,0,a)
#define all(a) (a).begin(), (a).end()

constexpr int MAX_N = 100;

int N;
int W[MAX_N], S;
bool dp[10001];

int main()
{
  scanf( "%d", &N );
  rep( i, N )
    scanf( "%d", W+i ), S += W[i];

  if( S % 2 == 1 )
  {
    puts("impossible");

    return 0;
  }

  dp[0] = true;
  rep( i, N ) for( int j = S; j >= 0; --j ) if( j-W[i] >= 0 )
    dp[j] |= dp[j-W[i]];

  puts( dp[S/2] ? "possible" : "impossible" );
  
  return 0;
}