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)

def double_helix(b):

    acgt = {"A":"T", "T":"A", "C":"G", "G":"C"}

    return acgt[b]
def main():
    b = str(input())
    print(double_helix(b))

if __name__ == '__main__':
    main()