#include <cstdio>
#include <cstdlib>
#include <iostream>
#include <string>
#include <cmath>
#include <algorithm>
#include <vector>
#include <queue>
#include <stack>

using namespace std;

int main(){
    int n,half=0,w[100];
    bool dp[5010]={false};
    
    scanf("%d",&n);
    
    for(int i=0;i<n;i++){
        scanf("%d",&w[i]);
        half+=w[i];
    }
    
    if(half%2){
        puts("impossible");
        return 0;
    }
    
    dp[0]=true;
    half/=2;
    
    for(int i=0;i<n;i++){
        for(int j=5000;j>=0;j--){
            if(dp[j] && j+w[i]<=5000){
                dp[j+w[i]]=true;
            }
        }
    }
    
    
    puts(dp[half] ? "possible" : "impossible");
    return 0;
}