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

#define REPR(i,s,e) for (int i = e-1; i >= s; i--)
#define repr(i,n) REPR(i,0,n)
#define REP(i,s,e) for (int i = s; i < e; i++)
#define rep(i,n) REP(i,0,n)

int main() {
    int n;
    cin >> n;
    vector<int> w(n);
    rep(i,n) cin >> w[i];

    int sum = accumulate(w.begin(),w.end(),0);
    vector<bool> dp(sum+1);
    dp[0] = true;
    rep(i,n) repr(j,sum+1) {
        if (dp[j])
            dp[j+w[i]] = true;
    }
    if (sum % 2 == 0 && dp[sum/2])
        cout << "possible" << endl;
    else
        cout << "impossible" << endl;

    return 0;
}