#include <iostream>
#include <iomanip>
#include <vector>
#include <algorithm>
#include <numeric>
#include <functional>
#include <cmath>
#include <queue>
#include <stack>

#define repd(i,a,b) for (int i=(a);i<(b);i++)
#define rep(i,n) repd(i,0,n)
#define MAX 10100
typedef long long ll;

using namespace std;


int inputValue(){
    int a;
    cin >> a;
    return a;
};

void inputArray(int * p, int a){
    rep(i, a){
        cin >> p[i];
    }
};

void inputVector(vector<int> * p, int a){
    rep(i, a){
        int input;
        cin >> input;
        p -> push_back(input);
    }
}

template <typename T>
void output(T a, int precision) {
    if(precision > 0){
        cout << setprecision(precision)  << a << "\n";
    }
    else{
        cout << a << "\n";
    }
}

int main(int argc, const char * argv[]) {
    
    // source code
    int N = inputValue();
    int W[100];
    int sum = 0;
    rep(i, N){
        W[i] = inputValue();
        sum += W[i];
    }
    bool P[MAX] = {false};
    P[sum / 2] = true;
    rep(i, N){
        rep(j, MAX){
            if (N - W[i] >= 0 && P[j] == true) {
                 P[j - W[i]] = true;
            }
        }
    }
    
    if (P[0] == true && sum % 2 == 0) {
        output("possible", 0);
    }
    else{
        output("impossible", 0);
    }
    
    return 0;
}