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

using namespace std;


int n;
vector<int> w;

int rec(int i, int j){
    int res;

    if(i==n){
        res = 0;
    }else if(j<w[i]){
        res = rec(i+1, j);
    }else{
        res = max(rec(i+1, j), rec(i+1, j-w[i])+w[i]);
    }

    return res;
}

int main(){

    cin>> n;
    int a, sum = 0;
    for(int i=0; i<n; i++){
        cin>> a;
        w.push_back(a);
        sum += w[i];
    }

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

    int ans = rec(0, W);
    if(ans==W){
        cout<< "possible"<< endl;
    }else{
        cout<< "impossible"<< endl;
    }

    return 0;
}