phi function

#include <iostream>
using namespace std;

int phi(int n) {
    int result = n; // Initialize result as n

    // Consider all prime factors of n and subtract their multiples from result
    for (int p = 2; p * p <= n; ++p) {
        if (n % p == 0) {
            while (n % p == 0)
                n /= p;
            result -= result / p;
        }
    }

    // If n has a prime factor greater than sqrt(n), subtract its multiple
    if (n > 1)
        result -= result / n;

    return result;
}

int main() {
    int n;
    cout << "Enter a number: ";
    cin >> n;

    int result = phi(n);
    cout << "Phi(" << n << ") = " << result << endl;

    return 0;
}