String Problem: Uppercase to Lowercase, Lowercase to Uppercase

Problem 70: Case Fix

You are given a string mixed with uppercase and lowercase letters . Your task is to write a program which will
flip the letters : (UpperCase -> LowerCase, LowerCase -> UpperCase)

Example:
INPUT:        OUTPUT:

eLepHanT   Elephant

cAt                  Cat

SuNDAY       Sunday

code:

not upto the output yet:

beautiful code with exacts output: