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

int main(){
    int N, V[1000];
    cin >> N;
    int sum = 0;
    for(int i = 0 ; i < N ; ++i)
    {
        cin >> V[i];
        sum += V[i];
    }
    if(N == 0 || sum%2 != 0)
    {
        cout << "impossible" << endl;
        return 0;
    }
    sum /= 2;
    
    bool dp[110][10010];
    memset(dp, 0, sizeof(dp));   // 一旦すべて false に
    dp[0][0] = true;             // dp[0][0] だけ true に

    for (int i = 0; i < N; ++i) 
    {
       for (int j = 0; j <= sum; ++j) 
       {
         dp[i+1][j] |= dp[i][j];
         if (j >= V[i]) dp[i+1][j] |= dp[i][j-V[i]];
        }
    }

    if (dp[N][sum]) cout << "possible" << endl;
    else cout << "impossible" << endl;
    return 0;
}