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 C (Clang 10.0.0) (judge verdict: Accepted)

#include <stdio.h>

#define N  4

int main(){
  const char abc[N] = "ABC";
  const char arc[N] = "ARC";
	char s[N];
  int abc_cnt = 0;
  int arc_cnt = 0;

  scanf("%s", s);

  for (int ii = 0; ii < N - 1; ii++) {
    if(s[ii] == abc[ii]){
      abc_cnt++;
    }
    if(s[ii] == arc[ii]) {
      arc_cnt++;
    }
  }

  if(abc_cnt == 3){
    puts("ARC");
  }else if(arc_cnt == 3){
    puts("ABC");
  }

  return 0;
}