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 (Clang 3.8.0) (judge verdict: Wrong Answer)

#include <iostream>
#include<algorithm>
#include<string>
#include <cmath>
#include <vector>
#include <map>
#include <cstdio>
#pragma region Macros
#define rep(i,n) for(int i=0;i<n;i++)
#define REP(i,n) for(int i=1;i<=n;i++)
#define int long long
#define all(x) (x).begin(),(x).end()
#define swap(a,b) (a += b,b = a - b,a -= b)
int gcd(int a, int b) // assuming a,b >= 1
{
    if (a < b)
        swap(a, b);
    if (b == 0)
        return a;
    if (a % b == 0)
        return b;
    return gcd(b, a % b);
}
int lcm(int a, int b) // assuming a,b >= 1
{
    return  a * b / gcd(a, b);
}
using namespace std;
#pragma endregion
signed main() {
    char b,c[128];
    c['A'] = 'T';
    c['T'] = 'A';
    c['C'] = 'T';
    c['T'] = 'C';
    cin >> b;
    cout << c[(int)b] << endl;
}