Reverse only alphabets(letters) in a string

Problem Name : Reverse only alphabets(letters) in a string. Problem description : Given a string, that contains special character together with alphabets (‘a’ to ‘z’ and ‘A’ to ‘Z’), reverse the string in a way that special characters are not affected. Example: Input : "c,a$t" Output : "t,a$c" Note that $ and , are not moved anywhere. Only subsequence "cat" is reversed. Input : "Vo,i,la!