#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <algorithm>
#include <functional>
#include <iostream>
#include <cstdio>
#include <cmath>
#include <cstdlib>
#include <ctime>
#include <cctype>
#include <string>
#include <cstring>

using namespace std;

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

  if (sum%2) {
    cout << "impossible" << endl;
    return 0;
  }

  bool memo[sum+1];
  memset(memo, false, sizeof(memo));
  for (int i = 0; i < n; i++) {
    for (int j = 0; j <= sum; j++) {
      if (j+w[i] >= sum) break;
      if (memo[j]) memo[j+w[i]] = true;
    }
    for (int j = 0; j < n; j++) {
      memo[w[i]] = true;
    }
  }

  if (memo[sum/2]) {
    cout << "possible" << endl;
  }else {
    cout << "impossible" << endl;
  }
}