#include <iostream>

// This program reads a string of characters
// terminated by a period and encode the characters as
// follows:
//    A -> Z
//    B -> A
//    C -> B
//    ...
//    Z -> Y

int main()
{
	char c;

	cout << "Enter a line of text terminated by 'enter': ";

	for (cin >> c; c != '.'; cin >> c) 
	{
		if (c == 'A')
			c = 'Z';
		else if (c == 'a')
			c = 'z';
		else if ((c >= 'a' && c <= 'z') ||
				 (c >= 'A' && c <= 'Z'))
			--c;

		cout << c;
	}
	cout << endl;
}