#include<bits/stdc++.h>
using namespace std;
int main(){
    int n;cin >> n;
    vector<int> w(n);
    bool dp[n+1][10001];
    int sum=0;
    for(int i=0;i<n;i++){
        cin >> w[i];
        sum+=w[i];
    }
    if(sum%2==1){
        cout << "impossible" << endl;
        return 0;
    }
    memset(dp,false,sizeof(dp));
    dp[0][0]=true;
    for(int i=0;i<n;i++){
        for(int j=0;j<10001;j++){
            if(dp[i][j]){
                dp[i+1][j]=true;
                dp[i+1][j+w[i]]=true;
            }
        }
    }
    if(dp[n][sum/2]){
        cout << "possible" << endl;
    }
    else{
        cout << "impossible" << endl;
    }
}