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: Runtime Error)

#include <stdio.h>
typedef long long ll;
typedef struct hoge{
    ll A;
    ll left;
    ll right;
}height;

int main(){
  ll N;
  ll ans=0;
  scanf("%lld",&N);
  height H[N];
  for(ll i = 0;i<N;i++){
    scanf("%lld",&H[i].A);
    H[i].left = i-H[i].A;
    H[i].right = i+H[i].A;
  }
  for(ll i = 0;i<N;i++) for(ll j = N-1;j>i;j--){
    if(H[i].right == H[j].left) ans++;
  }
  printf("%lld\n",ans);
  return 0;
}