PLEASE SOLVE WITH SIMPLE AND EASY WAY IN C. I HAVE A LIMITED TIME. THANK U SO MUCH!

Letters in a string: Write a program that asks the user to input a lowercase string, and outputs the unique characters that make up the string arranged in alphabetical order. For instance if the string is abracadabra, the output should be a,b,c,d,r Assume there are no spaces in the string. The integer code for the character 'a' is 97. C:\Users\win8\Desktop\3.exe Input string: abracadabra The letters of the string are: a, b, c, d, r Process exited, after 3.558 seconds with return value o Press any key to continue