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

int main() {
    ios::sync_with_stdio(false);
    int n; cin >> n;
    int a[n], b[n], c[n];
    for (int i = 0; i < n; i++) {
        cin >> a[i];
        if (i == 0)
            b[i] = a[i];
        else
            b[i] = a[i] + b[i-1];
    }
    c[n-1] = a[n-1];
    for (int i = n-2; i >=0; i--) {
        c[i] += c[i+1] + a[i];
    }


    sort(a, a+n);
    for (int i = n-1; i > 0 ; i--) {
        if (b[i] == c[i]) {
            cout << "possible\n";
            //printf("%d %d\n", a[i], b[i-1]);
            return 0;
        }
    }
    cout << "impossible\n";

    return 0;
}