#include <bits/stdc++.h>
using namespace std;
#define rep(i,n) for(int i = 0; i < (n);i++)
#define sz(x) int(x.size())
typedef long long ll;
typedef pair<int,int> P;

bool dp[10010];

int main(){
  int n;
  cin >> n;
  vector<int> W(n);
  int sum_W = 0;
  rep(i,n) cin >> W[i], sum_W += W[i];
 
  dp[0] = true;
  for (int i = 0; i < n; i++) {
    for (int w = sum_W-W[i]; w >= 0; w--) {
      dp[w+W[i]] |= dp[w]; 
    }
  }
  if (sum_W%2 != 0 || !dp[sum_W/2]) puts("impossible");
  else puts("possible");

  return 0;
}