Alien Invasion

#include <iostream>
#include <cmath>

using namespace std;

bool brute(unsigned long long n) {
    unsigned long long count = 0;
    for (unsigned long long i = 1; i <= n; i++) {
        if (n % i == 0) {
            count++;
        }
    }
    
    return count % 2 == 1;
}

bool less_brutal(unsigned long long n) {
    for (unsigned long long i = 1; i <= sqrt(n)+1; i++) {
        if (i*i == n) {
            return true;
        }
    }
    return false;
}

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

    /*for (unsigned long long i = 20000000000; ; i++) {
        cout << i << '\n';
        if (brute(i) != less_brutal(i)) {
            return 0;
        }
    }*/

    if (less_brutal(n)){
        cout << "odd" << endl;
    } else {
        cout << "even" << endl;
    }
    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: TIME LIMIT EXCEEDED

Test 21

Verdict: TIME LIMIT EXCEEDED

Test 22

Verdict: TIME LIMIT EXCEEDED