C++ iç içe if kullanımı

#include <iostream>

using namespace std;

int main() {
/* nested if else statement */
    int a;
    cout << "Enter a positive integer number: ";
    cin >> a;
    if (a < 20) {
        cout << "a is less than 20 ";
        if (a < 10)
            cout << "a is less than 10 ";
        else
            cout << "a is not less than 10 ";
    } else {
        if (a == 20) {
            cout << "a is equal to 20 ";
        } else
            cout << "a is greater than 20 ";
    }
    return 0;
}