#include <iostream>
using namespace std;

int main(void){
    int n,w[1005], sum = 0, m;
    bool dp[1005][1005];
    cin >> n;
    for(int i=0;i<n;i++){
        cin >> w[i];
        sum += w[i];
    }
    for(int i=0; i<1005;i++){
        for(int j=0;j<1005;j++){
            dp[i][j] = false;
        }
    }
    if(sum %2 == 1){
        cout << "impossible" << endl;
        return 0;
    }else{
        m = sum/2;
        dp[0][0] = true;
        for(int i=0; i<n;i++){
            for(int j=0;j<=m;j++){
                if(dp[i][j] == true){
                    dp[i+1][j+w[i]] =true;
                    dp[i+1][j] = true;
                }
            }
        }

    }
    if(dp[n][m] == true){
        cout << "possible" << endl;
    }else{
        cout << "impossible" << endl;
    }
    return 0;
}