#include <iostream>
#include <string>
using namespace std;

/**
   Returns a string of asterisks of the same length as 
   a given string.
   @param str a string such as "secret"
   @return a string with each character of str changed to a *,
   such as "******".
*/
string hide_characters(string str)
{
    string result;
    for (char ch [[maybe_unused]] : str) {
        result += '*';
    }
    return result;
}

int main()
{
    string s = "Hello";
    cout << s << endl;
    cout << hide_characters(s) << endl;

    s = "Goodbye"; 
    cout << s << endl;
    cout << hide_characters(s) << endl;

    s = "Now is the time for all good men to come to the aid of their country."; 
    cout << s << endl;
    cout << hide_characters(s) << endl;

    return 0;
}