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 <bits/stdc++.h>
using namespace std;

const char word[4] = {'A', 'C', 'G', 'T'};
const char change[4] = {'T', 'G', 'C', 'A'};

int main() {
    char b;
    cin >> b;
    for (int i = 0; i < 4; i++) {
        if (b == word[i]) {
            b = change[i];
            break;
        }
    }
    cout << b << endl;
}