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: Wrong Answer)

#include <bits/stdc++.h>
#include <math.h>
using namespace std;
typedef long long int ll;
template<class T> inline bool chmax(T& a, T b) {
  if (a < b) { a = b; return 1; }return 0; }
template<class T> inline bool chmin(T& a, T b) {
  if (a > b) { a = b; return 1; }return 0; }
#define all(a)  (a).begin(),(a).end()
#define rep(i, n) for (ll i = 0; i < n; i++)
#define vll vector<ll>
#define FOR(i, a, b) for (ll i = a; i < b; i++)
#define cinf(n,x) for(int i=0;i<(n);i++) cin >> x[i];
const ll INF =1LL << 62;

int main(){
  string a;
  cin >> a;
  if(a == "A"){
    cout << "T" << endl;
  }
  if(a == "T")
    cout << "A" << endl;
  if(a =="C")
    cout << "G" << endl;
  else
    cout << "C" << endl;
}