Problem:
Score : 100 points

Problem Statement

On the Planet AtCoder, there are four types of bases: A, C, G and T. A bonds with T, and C bonds with G.

You are given a letter b as input, which is A, C, G or T. Write a program that prints the letter representing the base that bonds with the base b.

Constraints

b is one of the letters A, C, G and T.

Input

Input is given from Standard Input in the following format:

b

Output

Print the letter representing the base that bonds with the base b.

Sample Input 1

A

Sample Output 1

T

Sample Input 2

G

Sample Output 2

C

Solution in C++14 (GCC 5.4.1) (judge verdict: Accepted)

#include<iostream>
#include<stdio.h>
#include<string>
#include<algorithm>
#include<math.h>
#include<vector>
#include<map>
using namespace std;
#define INF 999999999
#define lint long long
#define rep(i, n) for(int i = 1; i <= (int)(n); i++)
int gcd(int a,int b){return b?gcd(b,a%b):a;}
#define P pair<lint, lint>


int main(){
    string S;
    cin >> S;
    for(int i=0; i<S.length(); ++i){
        switch (S[i])
        {
            case 'A':
                cout << "T";
                break;
            case 'T':
                cout << "A";
                break;
            case 'C':
                cout << "G";
                break;
            case 'G':
                cout << "C";
                break;
            default:
                break;
        }
    }
    return 0;
}