#include <bits/stdc++.h>

using namespace std;


typedef int32_t h_int32;
typedef int64_t h_int64;
typedef uint32_t uh_int32;
typedef uint64_t uh_int64;
typedef h_int64 h_int;

#define REP( i, n ) for(int i = 0; i < ( int )( n ); ++i )
#define REPR( i, n ) for(int i = ( int )( n ); i >= 0; --i )
#define FOR( i, a, n ) for(int i = ( int )( a ); i < ( int )( n ); ++i )
#define FORR( i, a, n ) for(int i = ( int )( n ); i >= ( int )( a ); --i)

#define ALL( x ) x.begin(), x.end()

#define DOUT( x ) cerr << #x << " = " << x << "\n"
#define COUT( x ) cout << ( x ) << "\n"
#define DOUBLECOUT( num, x ) cout << fixed << setprecision( num ) << ( x ) << "\n"

#define INF 999999999
#define PI 3.14159265359

int n;
vector<int> v;
vector<int> vm;

bool f( int i, int left, int right )
{
        if( min( left, right ) + vm[i] < max( left, right ) ) return false;
        if(i == n) return left == right;
        if( f( i + 1, left + v[i], right ) ) return true;
        if( f( i + 1, left, right + v[i] ) ) return true;
        return false;
}

signed main()
{
        ios::sync_with_stdio( false );
        cin.tie( 0 );

        cin >> n;
        v.resize( n );
        vm.resize( n, 0 );
        REP( i, n )
        {
                cin >> v[i];
                vm[0] += v[i];
        }
        FOR( i, 1, n ) vm[i] = vm[i - 1] - v[i - 1];

        COUT( f( 0, 0, 0 ) ? "possible" : "impossible" );
        return 0;
}