package main

import . "fmt"

func main() {
	for {
		var c rune
		Scanf("%c",&c)
		if c<1 {
			Println()
			return
		}
		if c <'a' {
			Print(string(c+'a'-'A'))
		} else {
			Print(string(c-'a'+'A'))
		}
	}
}