#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    int dp[10001] = {0};
    int N;
    cin >> N;
    vector<int> W(N);
    int s = 0;
    for ( int i = 0; i < N; i++ ) {
        cin >> W[i];
        s += W[i];
    }
    if ( s%2 ) { cout << "impossible" << endl; return 0; }
    
    dp[0] = 1;
    for ( int i = 0; i < N; i++ ) {
        for ( int j = 10000; j >= 0; j-- ) {
            if ( dp[j] ) { dp[j+W[i]] = 1; }
        }
    }
    
    cout << ( dp[ s/2 ] ? "possible" : "impossible" ) << endl;
    
    return 0;
}