#include <iostream>
using std::cout, std::endl;

void count_letters(char str[], int& n_letters, int& n_digits, int& n_other) {
        while (*str) {
            if (*str >= 'a' && *str <= 'z' || *str >= 'A' && *str <= 'Z') {
                n_letters += 1;
            }
            else if (*str >= '0' && *str <= '9') {
                n_digits += 1;
            }
            else {
                n_other += 1;
            }
            str += 1;
        }
}

int main() {
    int n_letters = 0, n_digits = 0, n_other = 0;
    
    char s[] = "1n!2y#3a$";
    count_letters(s, n_letters, n_digits, n_other);

    cout << "letters: " << n_letters << endl << "digits: " << n_digits << endl << "n_other: " << n_other << endl;
}