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 <cstdio>
#include <cstdlib>
#include <cmath>
#include <cctype>
#include <climits>
#include <iostream>
#include <iomanip>
#include <algorithm>
#include <string>
#include <sstream>
#include <vector>
#include <map>
#include <set>
#include <complex>
#include <functional>
#include <utility>
#include <iterator>

#define REP(i, n) for(int i = 0; i < (int)(n); ++i)
#define FOR(i, m, n) for(int i = (m); i < (int)(n); ++i)
#define ALL(x) (x).begin(), (x).end()
#define INF 2000000000

#ifdef LOCAL
  #define dprintf(...) fprintf(stdout, __VA_ARGS__)
#else
  #define dprintf(...) 0
#endif

using namespace std;

int main() {
  char b;
  char ans;
  cin >> b;

  switch(b) {
    case 'A':
      ans = 'T';
      break;
    case 'T':
      ans = 'A';
      break;
    case 'C':
      ans = 'G';
      break;
    case 'G':
      ans = 'C';
      break;
  }

  cout << ans << '\n';
  return 0;
}