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

int p;
int w[101];
int ww[101];
int n;

bool dfs(int cur,int weight){
    if(weight==p) return true;
    if(cur==n) return false;
    if(weight>p) return false;
    if(dfs(cur+1,weight+w[cur])) return true;
    if(dfs(cur+1,weight)) return true;
    return false;
}

int main(){
    cin>>n;
    for(int i=0;i<n;i++) cin >> ww[i];
    int sum=0;
    for(int i=0;i<n;i++) sum+=ww[i];
    if(sum%2){
        cout << "impossible" << endl;
        return 0;
    }
    sort(ww,ww+n);
    for(int i=n-1;i>=0;i--){
        w[i] = ww[n-i-1];
    }
    p=sum/2;
    if(dfs(0,0)){
        cout << "possible" << endl;
    }else{
        cout << "impossible" << endl;
    }
    return 0;
}