/* -*- coding: utf-8 -*-
 *
 * 4.cc: No.4 おもりと天秤 - yukicoder
 */

#include<cstdio>
#include<cstdlib>
#include<cstring>
#include<cmath>
#include<iostream>
#include<string>
#include<vector>
#include<map>
#include<set>
#include<stack>
#include<list>
#include<queue>
#include<deque>
#include<algorithm>
#include<numeric>
#include<utility>
#include<complex>
#include<functional>
 
using namespace std;

/* constant */

const int MAX_N = 100;
const int MAX_A = 100;

/* typedef */

/* global variables */

int as[MAX_N];
bool dp[MAX_N * MAX_A / 2 + 1];

/* subroutines */

/* main */

int main() {
  int n;
  cin >> n;

  int sum = 0;
  for (int i = 0; i < n; i++) {
    cin >> as[i];
    sum += as[i];
  }

  if (sum & 1) {
    puts("impossible");
    return 0;
  }

  int h = sum / 2;
  dp[0] = true;

  for (int i = 0; ! dp[h] && i < n; i++)
    for (int j = h - as[i]; j >= 0; j--)
      if (dp[j]) dp[j + as[i]] = true;

  cout << (dp[h] ? "possible" : "impossible") << endl;
  return 0;
}