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

int main() {
    int N, sum = 0;
    int W[110];
    bool dp[110][10010];
    
    cin >> N;
    for(int i = 0; i < N; i++){
        cin >> W[i];
        sum+=W[i];
    }

    if(sum%2){
        cout << "impossible" << endl;
        return 0;
    }

    dp[0][0]=true;
    for(int i = 0; i < N; i++){
        for(int j = 0; j < sum/2+1; j++){
            dp[i+1][j] |= dp[i][j];
            dp[i+1][j+W[i]] |= dp[i][j];
        }
    }
    cout << (dp[N][sum/2]?"possible":"impossible") << endl;
    return 0;
}