#include <bits/stdc++.h>
using namespace std;
#define REP(i,n) for(int i=0; i<(n); i++)
#define REP2(i,x,n) for(int i=x; i<(n); i++) 
#define ALL(n) begin(n),end(n)
struct cww{cww(){ios::sync_with_stdio(false);cin.tie(0);}}star;
vector<vector<int>> visited( 100 + 1, vector<int>( 10000 + 1, -1 ) );
vector<int> W;
int N, total;
bool dfs( int i, int sum )
{
    if( i == N )
    {
       return sum == total / 2 && total % 2 == 0;
    }
    if( visited[ i ][ sum ] >= 0 )
    {
        return visited[ i ][ sum ];
    }
    return ( visited[ i ][ sum ] = dfs( i + 1, sum ) || dfs( i + 1, sum + W[ i ] ) );
    return ( visited[ i ][ sum ] = 0 );
}
int main()
{
    cin >> N;
    W.resize( N );
    for( auto &x : W )
    {
        cin >> x;
    }
    total = accumulate( ALL( W ), 0 );
    cout << ( dfs( 0, 0 ) ? "possible" : "impossible" ) << endl;
    return 0;
}