Problem:
Score : 100 points

Problem Statement

AtCoder Inc. holds a contest every Saturday.

There are two types of contests called ABC and ARC, and just one of them is held at a time.

The company holds these two types of contests alternately: an ARC follows an ABC and vice versa.

Given a string S representing the type of the contest held last week, print the string representing the type of the contest held this week.

Constraints

S is ABC or ARC.

Input

Input is given from Standard Input in the following format:

S

Output

Print the string representing the type of the contest held this week.

Sample Input 1

ABC

Sample Output 1

ARC

They held an ABC last week, so they will hold an ARC this week.

Solution in Ruby (2.7.1) (judge verdict: Wrong Answer)

CONTESTS= ["ABC","ARC"]
LAST_WEEK_CONTEST = "ABC"


input = gets.chomp.to_s
if input == "S"
 for this_week_contest in CONTESTS do
   unless LAST_WEEK_CONTEST == this_week_contest
     puts (this_week_contest)
     break
   end
 end
end