#include<stdio.h>
#include<iostream>

using namespace std;

int N;
int W[110];
int dp[10010];
int main(){
    cin >> N;
    int sum = 0;
    for(int i=0; i<N; i++) {
        cin >> W[i];
        sum += W[i];
    }
    if( sum % 2 ) {
        cout << "impossible" << endl;
        return 0;
    }
    sum /= 2;
    dp[0] = 1;
    for(int i=0; i<N; i++){
        for(int j=W[i]; j>=W[j]; j--){
            if( dp[j-W[i]] > 0 ) dp[j] = dp[j-W[i]] + 1;
        }
    }
    cout << ( dp[sum] ? "possible" : "impossible") << endl;
    return 0;
}