#include <iostream>
#include <string>
#include <vector>
#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstring>
#include <queue>
using namespace std;
#define MAX 114514

bool dp[MAX];

int main(){
    int N;
    cin >> N;
    int W[N], sum=0;
    for(int i=0; i<N; i++){
        cin >> W[i];
        sum += W[i];
    }
    dp[0] = true;
    for(int i=0; i<N ;i++){
        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" << endl;
    else cout << "possible" << endl;
}