Implementation approach

It is sufficient to “make the first letter lowercase” and “prepend Of” in order.

To “make the first letter lowercase,” we may rewrite the first letter with a new letter, or use a function that turns the entire string into lowercase (using the fact that the other characters are originally lowercase).

To “prepend Of,” the simplest way is to use a standard concatenation.

Sample code (Python 3 and C++)

The following is sample code in Python3.

s = input()
ans = "Of" + s.lower()
print(ans)

The following is sample code in C++.

#include <iostream>
using std::cin;
using std::cout;
#include <string>
using std::string;
#include <algorithm>
using std::tolower;

int main (void) {
	string s;
	cin >> s;
	
	string ans = s;
	ans[0] = tolower(ans[0]);
	ans = "Of" + ans;

	cout << ans << "\n";

	return 0;
}