#include <iostream>

using namespace std;

bool memo[5001]={};

int main(){
    int N,sum=0;
    cin>>N;
    memo[0]= true;
    int weight[100];
    
    for(int i=0;i<N;i++){
        cin>>weight[i];
        sum+=weight[i];
    }

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

    int half = sum/2;


    for(int i = 0; i<N;i++){
        for(int j=half;j>=0;j--){
            if(j-weight[i]<0)break;
            if(memo[j-weight[i]])
            memo[j]=true;
        }
    }

    if(memo[half])
    cout<<"possible"<<endl;
    else
    cout<<"impossible"<<endl;
}