#include <iostream>
#include <algorithm>
#include <string>
#include <vector>
#include <queue>
using namespace std;


int main(int argc, const char * argv[]) {
    int Max = 10000;
    int n;
    cin >> n;
    int w[n];
    int sum = 0;
    bool dp[Max];
    for (int i = 0; i < Max; i++) {
        dp[i] = false;
    }
    for (int i = 0; i < n; i++) {
        cin >> w[i];
        sum += w[i];
    }
    //片方が0の状態は必ず実現可能
    dp[0] = true;
    for (int i = 0; i < n; i++) {
        //それぞれの荷物について
        for (int j = Max - 1 - w[i]; j >= 0; j--) {
            //
            dp[j+w[i]] |= dp[j];
        }
    }
    if(sum % 2 == 1 || !dp[sum/2]){cout << "impossible";}
    else{cout << "possible";}
    cout << "\n";
}