#include <iostream>
#include <algorithm>
#include <vector>
#include <string>
#include <cstring>
#include <complex>
#include <stack>
#include <queue>
#include <map>

using namespace std ;

int main(){

    int n;
    cin >> n;
    int w[n];
    int m = 0;
    for(int i = 0; i < n; i++){
        cin >>  w[i];
        m += w[i];
    }
    if(m % 2 != 0){
        cout << "impossible" << endl;
        return 0;
    }else{
        m = m / 2;
    }
    vector<vector<bool>> p(n + 1,vector<bool>(m + 1));
    for(int j = 0; j < m; j++){
        p[0][j] = false;
    }
    for(int i = 0; i < n; i++){
        p[i][0] = true;
    }

    for(int i = 1; i <= n; i++){
        for(int j = 1; j <= m; j++){
            if(j - w[i] >= 0){
                p[i][j] = (p[i - 1][j] || p[i - 1][j - w[i]]);
            }else{
                p[i][j] = p[i - 1][j];
            }
        }
    }
    if(p[n][m]){
        cout << "possible" << endl;
    }else{
        cout << "impossible" << endl;
    }
    return 0;
}