You haven't specified the programming language so I am going to assume you need to do this in C++.
#include <iostream>
int main(int argc, int* argv[])
{
char origLetter;
std::cin >> origLetter;
switch (origLetter)
{
case 'a':
case 'A':
std::cout << "Alpha"; break;
case 'b':
case 'B':
std::cout << "Beta"; break;
default:
std::cout << "Unknown";
}
std::cout << std::endl;
}
Hope this helps.