#include <iostream>
using namespace std;

bool dp[5010];
int W[111];

int main(){
    int N;
    cin >> N;
    
    int w_sum = 0;
    for(int i=0;i<N;i++){
        cin >> W[i];
        w_sum += W[i];
    }
    
    if(w_sum % 2 != 0){
        cout << "impossible" << endl;
    } else {
        w_sum /= 2;
        dp[0] = true;
        
        for(int i=0;i<N;i++){
            int w = W[i];
            
            for(int sum=w;sum<=w_sum;sum++){
                dp[sum] |= dp[sum-w];
            }
        }
        
        cout << (dp[w_sum] ? "possible" : "impossible") << endl;
    }
    
    return 0;
}