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 Python (3.4.3) (judge verdict: Accepted)

# -*- coding: utf-8 -*-
"""
Created on Mon Apr  1 22:23:40 2019

@author: Owner
"""
a = []
b = str(input())

for item in b:
    if item == "A":
        item_mod = item.replace("A","T")
    if item == "G":
        item_mod = item.replace("G","C")
    if item == "T":
        item_mod = item.replace("T","A")
    if item == "C":
        item_mod = item.replace("C","G")
    a.append(item_mod)
print(a[0])