#include<iostream>
using namespace std;
int main(){
    int N,sum=0;
    int W[100];
    bool dp[100][5001] = {};
    int i,j;
    cin >> N;
    for(i=0;i<N;i++){
        cin >> W[i];
        sum += W[i];
    }
    if(sum%2 != 0){
        cout << "impossible" << endl;
        return 0;
    }
    sum /= 2;
    for(i=0;i<N;i++) dp[i][0] = true;
    dp[0][W[0]] = true;
    for(i=1;i<N;i++){
        for(j=1;j<=sum;j++){
            if(W[i] <= j && dp[i-1][j-W[i]]) dp[i][j] = true;
            if(dp[i-1][j]) dp[i][j] = true;
        }
    }
    if(dp[N-1][sum]) cout << "possible" << endl;
    else cout << "impossible" << endl;
    return 0;
}