#include <bits/stdc++.h>
using namespace std;
int n;
int w[101];
int sum;
int dp[101][1000001];



int recu(int N, int W){
    int res = 0;
    if (dp[N][W] > -1) return dp[N][W];
    if (N <= 0 && W > 0){
        dp[N][W] = 0;
        return dp[N][W];
    }
    if (W == 0){
        dp[N][W] = 1;
        return dp[N][W];
    }
    res = recu(N - 1,W);
    if (w[N - 1] <= W){
        res += recu(N - 1, W - w[N - 1]);
    }
    return res;
    
}

int main(){
    memset(dp,-1, sizeof(dp));
    sum = 0;
    dp[0][0] = 1;
    cin >> n;
    for (int i = 0; i < n; ++i){
        cin >> w[i];
        sum += w[i];
    }
    if (sum%2 != 0){
        cout << "impossible" << endl;
        return 0;
    }
    sum = sum/2;
    int res = recu(n, sum);
    if (res > 0) cout << "possible" << endl;
    else cout << "impossible" << endl;
    
}