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<bits/stdc++.h>
#define rep(i,n) for(int i = 0; i < (n); i++) 
using namespace std;
#define N_SIZE 100000

int main(void){
int i,n,m,a,b,count=0;
vector<int> h(n);
vector<bool> ok(n,true);
cin >> n >> m;
rep(i,n){
cin >> h.at(i);
}

rep(i,m){
    cin >> a >> b;
    a--;
    b--;
    if(h.at(a) > h.at(b)){
    ok.at(b)=false;  
    }
    else if(h.at(a) < h.at(b)){
    ok.at(a)=false;  
    }
    else{
    ok.at(a)=false;
    ok.at(b)=false;
    }
}
rep(i,n){
//cout << buf.at(i) << endl;
    if(ok.at(i))
    count++;
}
cout << count << endl;

}