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 (GCC 9.2.1) (judge verdict: Wrong Answer)

#include <stdio.h>

int main(void){
  int minus[2000100]={};
  int i,j;
  int n;
  long long int ans=0;
  scanf("%d",&n);
  int a[n];
  for(i=0;i<n;i++){
    scanf("%d",&a[i]);
    if((i-a[i])>0){
      ans+=minus[i-a[i]];
    }
    if((i+a[i])<(n+2)){
      minus[i+a[i]]+=1;
    }
  }
  printf("%lld",ans);
  
  return 0;
}