#include <bits/stdc++.h>

using namespace std;

int N, H;
int heavy[100] = {0};
bool used[100] = {false};
bool dp[10001] = {false};

bool rec(int sum = 0){
    
    if(sum > H) return false;
    if(sum == H) return true;
    
    if(dp[sum]) return false;
    dp[sum] = true;
    
    
    int i;
    bool flag = false;
    for(i = 0; i < N; ++i){
        if(!used[i]){
            used[i] = true;
            flag = rec(sum + heavy[i]);
            used[i] = false;
        }
        if(flag) break;
    }
    
    return flag;
}

int main(void){
    
    cin >> N;
    
    int i, n = 0;
    for(i = 0; i < N; ++i){
        cin >> heavy[i];
        n += heavy[i];
    }
    
    if(n % 2 == 1){
        cout << "impossible" << endl;
    }
    else{
        H = n / 2;
        if(rec()) cout << "possible" << endl;
        else cout << "impossible" << endl;
    }
    
    return 0;
}