#include <iostream>
#include <algorithm>
using namespace std;

int main(){
    int n;cin>>n;
    int w[101];
    int sum=0;
    for(int i=0;i<n;i++){
        cin>>w[i];
        sum += w[i];
    }
    if(sum%2){
        cout << "impossible" << endl;
        return 0;
    }
    bool score[10001];
    fill(score,score+10001,false);
    score[0]=true;
    for(int i=0;i<n;i++){
        for(int j=10000;j>=0;j--){
            if(score[j]) score[j+w[i]]=true;
        }
    }
    
    if(score[sum/2]){
        cout << "possible" << endl;
    }else{
        cout << "impossible" << endl;
    }
   
    return 0;
}