#include<iostream>
#include<stdio.h>
#include<vector>
#include<algorithm>

using namespace std;

int main(){

    int n;
    cin>> n;
    vector<int> w(n+1);

    int sum = 0;
    for(int i=1; i<n+1; i++){
        cin>> w[i];
        sum += w[i];
    }

    int W;
    if(sum%2==1){
        cout<< "impossible"<< endl;
        return 0;
    }else{
        W = sum/2;
    }

    int dp[n+1][W+1];
    for(int i=0; i<n+1; i++){
        dp[i][0] = 0;
    }
    for(int j=0; j<W+1; j++){
        dp[0][j] = 0;
    }

    for(int i=1; i<n+1; i++){
        for(int j=1; j<W+1; j++){
            if(j<w[i]){
                dp[i][j] = dp[i-1][j];
            }else{
                dp[i][j] = max(dp[i-1][j], dp[i-1][j-w[i]]+w[i]);
            }
        }
    }

    if(dp[n][W]==W){
        cout<< "possible"<< endl;
    }else{
        cout<< "impossible"<< endl;
    }

    return 0;
}