#include <iostream>
using namespace std;
bool dp[100][10010];
int main(){
    int n;cin>>n;
    int sm = 0;
    int a[n];
    for(int i = 0; n > i; i++){
        cin>>a[i];
        sm += a[i];
    }
    if(sm%2){
        cout << "impossible" << endl;
        return 0;
    }
    dp[0][0] = true;
    dp[0][a[0]] = true;
    for(int i = 1; n > i; i++){
        for(int j = 0; 10000 >= j; j++){
            if(dp[i-1][j]){
                //cout << i << " " << j << endl;
                dp[i][j] = true;
            }
            if(a[i]<=j && dp[i-1][j-a[i]]){
                //cout << i << " " << j << endl;
                dp[i][j] = true;
            }
        }
    }
    if(dp[n-1][sm/2]){
        cout << "possible" << endl;
    }else{
        cout << "impossible" << endl;
    }
    
}