#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int n;cin>>n;
    int w[101];
    for(int i=0;i<n;i++) cin >> w[i];
    int sum=0;
    for(int i=0;i<n;i++) sum += w[i];
    int sum2=0;
    for(int i=n-1;i>=0;i--){
        sum -= w[i];
        sum2 += w[i];
        if(sum==sum2){
            cout << "possible" << endl;
            return 0;
        }
    }
    cout << "impossible" << endl;
    return 0;
}