Alien Invasion

#include <iostream>
#include <cmath>
#include <algorithm>

using namespace std;

typedef long long ll;



int main() {
  ll x;

  cin >> x;

  ll xx = sqrt(x);
  const ll N = 1000000;

  for (ll a = xx-N; a <= xx+N; a++) {
    if (a*a == x) {
      cout << "odd\n";
      return 0;
    }
  }

  cout << "even\n";
  return 0;
  
}

Test 1

Verdict: ACCEPTED

Test 2

Verdict: ACCEPTED

Test 3

Verdict: ACCEPTED

Test 4

Verdict: ACCEPTED

Test 5

Verdict: ACCEPTED

Test 6

Verdict: ACCEPTED

Test 7

Verdict: ACCEPTED

Test 8

Verdict: ACCEPTED

Test 9

Verdict: ACCEPTED

Test 10

Verdict: ACCEPTED

Test 11

Verdict: ACCEPTED

Test 12

Verdict: ACCEPTED

Test 13

Verdict: ACCEPTED

Test 14

Verdict: ACCEPTED

Test 15

Verdict: ACCEPTED

Test 16

Verdict: ACCEPTED

Test 17

Verdict: ACCEPTED

Test 18

Verdict: ACCEPTED

Test 19

Verdict: ACCEPTED

Test 20

Verdict: ACCEPTED

Test 21

Verdict: ACCEPTED

Test 22

Verdict: ACCEPTED