#include <bits/stdc++.h>
using namespace std;

int N;
int w[100];
int arr[101][20001];
int* dp[101];

int main(){
    scanf("%d", &N);
    for(int x = 0; x < N; x++){
        scanf("%d", w+x);
        fill(arr[x], arr[x]+20001, 0);
        dp[x] = arr[x] + 10000;
    }
    dp[N] = arr[N] + 10000;
    dp[0][0] = 1;
    for(int x = 0; x < N; x++){
        for(int y = -10000; y <= 10000; y++){
            if(dp[x][y]){
                dp[x + 1][y + w[x]] = 1;
                dp[x + 1][y - w[x]] = 1;
            }
        }
    }
    if(dp[N][0]){
        puts("possible");
    }else{
        puts("impossible");
    }
    return 0;
}