#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <algorithm>
#include <vector>



int main(){
  int  n;
  std::cin >> n;
  int *w = (int*)malloc(sizeof(int)* n);
  for(register int i =0; i < n; i++)
    std::cin >> w[i];
  long sum;
  sum = 0;
  for(register int i = 0; i < n; i++)
    sum += w[i];
  bool *dp = (bool*)malloc(sizeof(bool) * (sum + 1));
  dp[0] = true;
  if(sum % 2) dp[n-1] = false;
  else{
    for(register long i = 0; i < n; i++){
      for(register long j = sum/2; i - 1  < j; j--){
	dp[j] |= dp[j-i];
      }
    } 
  }
  if(dp[sum/2] == true) std::cout << "possible" << std::endl;
  else std::cout << "impossible" << std::endl;
}