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 (Python):
import sys
stdin = sys.stdin
read_int = lambda : list(map(int,stdin.readline().split()))
read_str = lambda : stdin.readline().rstrip()

S = read_str()

dic = {'A':'T','T':'A','C':'G','G':'C'}

print(dic[S])

Solution (Python):

"""
Created on Sun Mar 24 21:12:06 2019

@author: yuta
"""

B = input()

def main(b):
    if b == "A":
        print("T")
    elif b == "C":
        print("G")
    elif b == "G":
        print("C")        
    elif b == "T":
        print("A")
main(B)

Solution (Python):
S = input()
if S == "A":
  print("T")
elif S == "T":
  print("A")
elif S == "C":
  print("G")
elif S == "G":
  print("C")

Solution (Python):
b = input()
twin = {"A":"T","T":"A","C":"G","G":"C"}
print(twin[b])

Solution (Python):
b = input()
if b == "A":
  print("T")
elif b == "T":
  print("A")

elif b == "C":
	print("G")
else:
   	print("C")

Solution (Python):
b = input()
if  b == "A":
    print("T")
elif b == "T":
    print("A")
elif b == "G":
    print("C")
else:
    print("G")

Solution (Python):


from collections import deque
import itertools as it
import sys
import math

sys.setrecursionlimit(1000000)

INF = 10 ** 18
MOD = 10 ** 9 + 7

b = raw_input()
b = b.replace('A', '1').replace('T', '2').replace('C', '3').replace('G', '4')
b = b.replace('1', 'T').replace('2', 'A').replace('3', 'G').replace('4', 'C')
print b

Solution (Python):
import sys

def main():
  input = sys.stdin.readline
  b = str(input().strip())
  if b == 'A':
    print('T')
  elif b == 'T':
    print('A')
  elif b == 'G':
    print('C')
  else:
    print('G')

if __name__ == '__main__':
  main()

Solution (Python):
b = input()

if b == 'A':
  print('T')
elif b == 'T':
  print('A')
elif b == 'G':
  print('C')
else:
  print('G')

Solution (Python):
dic = {"A":"T", "C":"G", "T":"A", "G":"C"}
print(dic[input()])

Solution (Python):
s=str(input())
d=dict()
d['A']='T'
d['T']='A'
d['C']='G'
d['G']='C'
print(d[s])

Solution (Python):
b, = map(str, input().split())

if b == "A":
    print("T")
elif b == "T":
    print("A")     
elif b == "C":
    print("G") 
else:
    print("C")

Solution (Python):
b=input()

if b==("A"):
	print ("T")
elif b==("T"):
	print ("A")
elif b==("G"):
    	print ("C")
elif b==("C"):
	print ("G")
else:
    pass

Solution (Python):
s=input()
tex =[]
for i in s:
  if i=="A":
    tex.append("T")
  elif i=="T":
    tex.append("A")
  elif i=="G":
    tex.append("C")
  elif i=="C":
    tex.append("G")
    
print("".join(tex))

Solution (Python):
def main():
    a = input()
    if a == "A":
        print("T")
    elif a == "T":
        print("A")
    elif a == "C":
        print("G")
    elif a == "G":
        print("C")


if __name__ == '__main__':
    main()

Solution (Python):
inp = input()

if inp == 'A':
    print('T')
elif inp == 'T':
    print('A')
elif inp == 'C':
    print('G')
else:
    print('C')

Solution (Python):


b = input()

def getAns(b) :
    if 'A' == b :
        return "T"
    elif 'T' == b :
        return "A"
    elif 'C' == b :
        return "G"
    elif 'G' == b :
        return "C"
    else :
        return ""

print(getAns(b))

Solution (Python):
b = input()
if b == "A":
  print("T")
elif b == "T":
  print("A")
elif b == "C":
  print("G")
else:
  print("C")

Solution (Python):

mp = list('ACGT')
print('TGCA'[mp.index(input())])

Solution (Python):
b=input()

if b=='A':
  print('T')
elif b=='T':
  print('A')
elif b=='C':
  print('G')
else:
  print('C')

Solution (Python):
b=input()

e_dict={
  'A':'T',
  'T':'A',
  'G':'C',
  'C':'G'
}

print(e_dict[b])

Solution (Python):
dic = {'A':'T','T':'A','C':'G','G':'C'}
print(dic[input()])

Solution (Python):
enki = input()
if enki == "A":
	print("T")
elif enki == "T":
	print("A")
elif enki == "C":
	print("G")
else:
	print("C")

Solution (Python):
b = input()

if b == 'A':
	print('T')
elif b == 'T':
	print('A')
elif b == 'C':
	print('G')
else:
	print('C')

Solution (Python):
b = input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'G':
    print('C')
else:
    print('G')

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print("G")
elif b =="G":
    print("C")

Solution (Python):
b=input()
a={"A":"T","T":"A","C":"G","G":"C"}
print(a[b])

Solution (Python):
b = input()
if b == "A":
    print("T")
elif b == "T":
    print("A")
elif b == "C":
    print("G")
elif b == "G":
    print("C")

Solution (Python):
s = input()
if s == 'A':
    ss = 'T'
elif s == 'T':
    ss = 'A'
elif s == 'G':
    ss = 'C'
elif s == 'C':
    ss = 'G'

print(str(ss))

Solution (Python):
b = input()
M = {'A': 'T', 'C': 'G', 'T': 'A', 'G': 'C'}
R = M[b]
print(R)

Solution (Python):
i = input()
table = str.maketrans({'A':'T', 'T':'A', 'G':'C', 'C':'G'})
print(i.translate(table))

Solution (Python):
b = input()
if b=="A":
  print("T")
elif b=="T":
  print("A")
elif b=="C":
  print("G")
elif b=="G":
  print("C")

Solution (Python):
d=input()

srch=['A','C','G','T']
corr=['T','G','C','A']

i=srch.index(d)
print(corr[i])

Solution (Python):
A = str(input())

if A == "A":
    print('T')
elif A == "T":
    print('A')
elif A == "C":
    print('G')
elif A == "G":
    print('C')

Solution (Python):






b = str(input())





if b == "A":
    print("T")
elif b == "C":
    print("G")
elif b == "G":
    print("C")
elif b == "T":
    print("A")
else:
    print("error")

Solution (Python):
b=input()
if b=='A':
    print('T')
elif b=='T':
    print('A')
elif b=='C':
    print('G')
else:
    print('C')

Solution (Python):
b = input()
l = ["A", "C", "G", "T"]
if b == "A":
    print("T")
elif b == "C":
    print("G")
elif b == "T":
    print("A")
else:
    print("C")

Solution (Python):
base = input()
if base == 'A':
    print('T')
elif base == 'T':
    print('A')
elif base == 'C':
    print('G')
elif base == 'G':
    print('C')

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b =='T':
    print('A')
elif b == 'C':
    print('G')
else:
    print('C')

Solution (Python):
chara = input()

if chara=='A':
  print('T')
elif chara=='T':
  print('A')
elif chara=='G':
  print('C')
else:
  print('G')

Solution (Python):
acgt = ['A','C','G','T']
tai = ['T','G','C','A']
b = input()
print(tai[acgt.index(b)])

Solution (Python):
b = input()

if b == "A":
  print("T")
if b == "T":
  print("A")
  
if b == "C":
  print("G")
if b == "G":
  print("C")

Solution (Python):
C = input()
if C == 'A':
  print('T')
elif C == 'T':
  print('A')
elif C == 'C':
  print('G')
else:
  print('C')

Solution (Python):
b = input()

if b == 'A':
    ans = 'T'
elif b == 'T':
    ans = 'A'
elif b == 'C':
    ans = 'G'
else:
    ans = 'C'

print(ans)

Solution (Python):
if __name__ == '__main__':
  b = input()
  if b == 'A':
    print('T')
  elif b == 'T':
    print('A')
  elif b == 'G':
    print('C')
  elif b == 'C':
    print('G')

Solution (Python):
x=input()
if x=="A" :
    print("T")
elif x=="C" :
    print("G")
elif x=="G" :
    print("C")
else:
    print("A")

Solution (Python):
b = input()
if b == "A":
  print("T")
elif b == "T":
  print("A")
elif b == "C":
  print("G")
elif b == "G":
  print("C")

Solution (Python):

k = input()
jisyo = {"A":"T", "C":"G", "G":"C", "T":"A"}
print(jisyo[k])

Solution (Python):
a = input()

if a == "A":
	a = "T"
elif a == "T":
	a = "A"
elif a == "G":
	a = "C"
elif a == "C":
	a = "G"
print(a)

Solution (Python):
a = input()


if a=="A": print("T")
if a=="T": print("A")
if a=="C": print("G")
if a=="G": print("C")

Solution (Python):
b = input()
if b == "A":
    print("T")
elif b == "C":
    print("G")
elif b == "G":
    print("C")
else:
    print("A")

Solution (Python):
a=input() 

def enki(a):
    if a == "A":
        print("T")
    elif a == "C":
        print("G")
    elif a == "G":
        print("C")
    else:
        print("A")

enki(a)

Solution (Python):
from sys import exit



S = str(input())


if S == "A":
    print("T")
elif S == "T":
    print("A")
elif S == "G":
    print("C")
elif S == "C":
    print("G")

Solution (Python):
a=input()
if a=="A":
  print("T")
if a=="T":
  print("A")
if a=="C":
  print("G")
if a=="G":
  print("C")

Solution (Python):


a = input()
 
if a == 'A':
    print('T')
elif a == 'T':
    print('A')
elif a == 'G':
    print('C')
else:
    print('G')

Solution (Python):
a = input()
if(a=="A"):
    print("T")
elif(a=="T"):
    print("A")
elif(a=="C"):
    print("G")
else:
    print("C")

Solution (Python):
b = input()
if b == "A":
    print("T")
if b == "T":
    print("A")
if b == "G":
    print("C")
if b == "C":
    print("G")

Solution (Python):
s=input()
d={'A':'T','C':'G','G':'C','T':'A'}
print(d[s])

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b=='C':
    print('G')
elif b=='G':
    print('C')

Solution (Python):

b = input()

pair = {
    'A': 'T',
    'C': 'G',
    'G': 'C',
    'T': 'A'
}

print(pair[b])

Solution (Python):

b = input()

if b == "A":
  print("T")
elif b == "T":
  print("A")
elif b == "G":
  print("C")
elif b == "C":
  print("G")

Solution (Python):
def A():
    
    b = input()
    helyx = {'A':'T', 'T':'A', 'C':'G', 'G':'C'}

    print(helyx[b])


if __name__ == '__main__':
    A()

Solution (Python):
b = input()

if b == 'A':
  print('T')
elif b == 'T':
  print('A')
elif b == 'G':
  print('C')
else:
  print('G')

Solution (Python):
character = input()

if character == 'A':
    print('T')
elif character == 'T':
    print('A')
elif character == 'C':
    print('G')
elif character == 'G':
    print('C')

Solution (Python):



import sys
import math


n = input()

if n == 'A':
    print('T')
if n == 'T':
    print('A')
if n == 'G':
    print('C')
if n == 'C':
    print('G')

Solution (Python):
a = input()

if a == "A":
    a = "T"
elif a == "T":
    a = "A"
elif a == "C":
    a = "G"
else:
    a="C"
print(a)

Solution (Python):
b = input()
if b == "A" :
    print("T")
elif b ==  "T" :
    print("A")
elif b == "C" :
    print("G")
else :
    print("C")

Solution (Python):
b = str(input())

if b == 'A':
  print('T')
elif b == 'T':
  print('A')
elif b == 'C':
  print('G')
elif b == 'G':
  print('C')

Solution (Python):

b = input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
else:
    print('C')

Solution (Python):
word=input()
if word == 'A':
  print('T')
elif word == 'T':
  print('A')
elif word == 'G':
  print('C')
else:
  print('G')

Solution (Python):
x = input()

if x == 'A':
    y = 'T'
elif x == 'T':
    y = 'A'
elif x == 'G':
    y = 'C'
else:
    y = 'G'
print(y)

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
else:
    print('C')

Solution (Python):
b = input()
if b == 'A':
  print('T')
elif b == 'T':
  print('A')
elif b == 'G':
  print('C')
elif b == 'C':
  print('G')

Solution (Python):
x = input()
if x == "A" :
  print("T")
elif x == "T":
  print("A")
elif x == "C":
  print("G")
else:
  print("C")

Solution (Python):
b = input()
if(b=="A"):
    print("T")
elif(b=="T"):
    print("A")
elif(b=="G"):
    print("C")
else:
    print("G")

Solution (Python):
b = input()
if(b == 'A'):
    print('T')
elif(b == 'T'):
    print('A')
elif(b == 'G'):
    print('C')
else:
    print('G')

Solution (Python):
b = input()
dic = {"A":"T","C":"G","G":"C","T":"A"}
print(dic[b])

Solution (Python):
b=input()
if b == "A":
  print("T")
elif b == "G":
  print("C")
elif b == "C":
  print("G")
elif b == "T":
  print("A")

Solution (Python):


import sys

def parse_input(lines_as_string = None):


    lines = []
    if lines_as_string is None:
        lines.append(input())
    else:
        lines = [e for e in lines_as_string.split("\n")][1:-1]
 
    tokens = lines[0].split(" ")
    b = tokens[0]

    return (b,)


def solve(b):
    
    m = {
        "A": "T",
        "C": "G",
        "G": "C",
        "T": "A",
    }

    return m[b]

def main():
    

    print("%s" % solve(*parse_input()))

if __name__ == '__main__':

    main()

Solution (Python):
""" AtCoder """

b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == ('C'):
    print('G')
else:
    print('C')

Solution (Python):
from sys import stdin

def main():
    B = input()

    s1 = {'A', 'T'}
    s2 = {'C', 'G'}
    if B in s1:
        ans = {B} ^ s1
    else:
        ans = {B} ^ s2
    print(*ans)

input = lambda: stdin.readline().rstrip()
main()

Solution (Python):
b = input()
if b == "A":
    print("T")
elif b == "T":
    print("A")
elif b == "C":
    print("G")
else:
    print("C")

Solution (Python):
b=input()
if(b=='A'):
    print('T')
if(b=='C'):
    print('G')
if(b=='G'):
    print('C')
if(b=='T'):
    print('A')

Solution (Python):
b = input()

if b == 'A':
	print('T')
elif b == 'T':
	print('A')
elif b == 'G':
	print('C')
else:
	print('G')

Solution (Python):
b=input()
enki=[["A","T"],["T","A"],["C","G"],["G","C"]]
[print(i[1]) for i in enki if b==i[0]]

Solution (Python):

b = input()

if b == 'A': b = 'T'
elif b == 'T': b = 'A'
elif b == 'C': b = 'G'
elif b == 'G': b = 'C'

print(b)

Solution (Python):
s = input()
if s == 'A':
    print('T')
elif s == 'C':
    print('G')
elif s == 'G':
    print('C')
else:
    print('A')

Solution (Python):
def change(string):
  if string == "A":
    return "T"
  elif string == "T":
    return "A"
  elif string == "G":
    return "C"
  elif string == "C":
    return "G"
  
if __name__ == "__main__":
  string = input()
  print(change(string))

Solution (Python):
b = input()

if b == 'A':
    a = 'T'
elif b == 'C':
    a = 'G'
elif b == 'G':
    a = 'C'
elif b == 'T':
    a = 'A'

print(a)

Solution (Python):
b = list(input())
for i in range(0, len(b)):
    if b[i] == 'A':
        b[i] = 'T'
    elif b[i] == 'T':
        b[i] = 'A'
    elif b[i] == 'G':
        b[i] = 'C'
    else:
        b[i] = 'G'
print("".join(b))

Solution (Python):
dict = {
    "A": "T",
    "C": "G",
    "T": "A",
    "G": "C"
}
s = input()
print(dict.get(s))

Solution (Python):
x = input()
if x == "A":
  print("T")
elif x == "T":
  print("A")
elif x == "C":
  print("G")
elif x == "G":
  print("C")
else:
  print("")

Solution (Python):
b=str(input())
if b=='A':
    print('T')
elif b=='C':
    print('G')
elif b=='G':
    print('C')
else:
    print('A')

Solution (Python):
b=input()
if b=='A':
    print('T')
elif b=='T':
    print('A')
elif b=='C':
    print('G')
else:
    print('C')

Solution (Python):
s = str(input())
if s == 'A':
    print('T')
elif s=='T':
    print('A')
elif s=='G':
    print('C')
elif s=='C':
    print('G')

Solution (Python):
b = input()
if b == "A":
    ans = "T"
elif b == "T":
    ans = "A"
elif b == "G":
    ans = "C"
else:
    ans = "G"

print(ans)

Solution (Python):
A = input()
if A == "A":
  print("T")
elif A == "T":
  print("A")
elif A == "C":
  print("G")
elif A == "G":
  print("C")

Solution (Python):
s = input()

if s == 'A':
    print('T')
elif s == 'C':
    print('G')
elif s == 'G':
    print('C')
else:
    print('A')

Solution (Python):
b = list(input())
res = []
for i in range(len(b)):
    if b[i] == 'A':
        res.append("T")
    elif b[i] == 'T':
        res.append('A')
    elif b[i] == 'C':
        res.append('G')
    elif b[i] == 'G':
        res.append('C')

print(''.join(res))

Solution (Python):
def main():
    acgt = {"A": "T", "T": "A", "C": "G", "G": "C"}
    b = input()
    print(acgt[b])


if __name__ == "__main__":
    main()

Solution (Python):
b = input()
ans = 'C'
if b ==  'A':
        ans = 'T'
if b == 'C':
        ans = 'G'
if b == 'T':
        ans = 'A'
print(ans)

Solution (Python):
a = input()
if a == 'A': print('T')
elif a == 'T':print('A')
elif a == 'C': print('G')
else:print('C')

Solution (Python):
b=input()

if b=="A":
    print("T")
if b=="T":
    print("A")
if b=="C":
    print("G")
if b=="G":
    print("C")

Solution (Python):
def main():
    s = input()
    s = s.replace("A", "K").replace("T", "A").replace("K", "T")
    s = s.replace("G", "K").replace("C", "G").replace("K", "C")
    print(s)


if __name__ == '__main__':
    main()

Solution (Python):
enki = {"A":"T", "C":"G", "G":"C", "T":"A"}
print(enki[str(input())])

Solution (Python):
b = input()
if b == 'A': print('T')
if b == 'T': print('A')
if b == 'C': print('G')
if b == 'G': print('C')

Solution (Python):
b = input()

dna = ["A", "C", "G", "T"]

rna = ["T", "G", "C", "A"]

idx = dna.index(b)
print(rna[idx])

Solution (Python):
n=input()
if n=='A':
  ans='T'
if n=='T':
  ans='A'
if n=='C':
  ans='G'
if n=='G':
  ans='C'
print(ans)

Solution (Python):
b = input()

if (b == "A") :
    print("T")
elif (b == "T") :
    print("A")
elif (b == "C") :
    print("G")
elif (b == "G") :
    print("C")

Solution (Python):
b = input()

if (b == 'A'):
    print('T')
if (b == 'T'):
    print('A')
if (b == 'G'):
    print('C')
if (b == 'C'):
    print('G')

Solution (Python):


str = input()

if str =='A' :
    str = 'T'
elif str == 'T' :
    str = 'A'
elif str == 'C':
    str = 'G'
elif str == 'G':
    str = 'C'

print(str)

Solution (Python):
import numpy as np
import sys

A = input()

def f(x):
    if A == "A":
        return "T"
    elif A == "T":
        return "A"
    elif A == "G":
        return "C"
    else:
        return "G"

print(f(A))

Solution (Python):
n = input()
if n=="A":
  print("T")
elif n=="T":
  print("A")
elif n=="G":
  print("C")
else:
  print("G")

Solution (Python):
b=input()
 
if b=="A":
    print("T")
elif b=="T":
    print("A")
elif b=="G":
    print("C")
elif b=="C":
    print("G")

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
elif b == 'G':
    print('C')

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
elif b == 'G':
    print('C')
else:
    print('This is not the base')

Solution (Python):
b = input()

if (b == 'A'):
    print('T')
if (b == 'T'):
    print('A')
if (b == 'G'):
    print('C')
if (b == 'C'):
    print('G')

Solution (Python):
word = input()
if word == "A":
  print("T")
elif word == "T":
  print("A")
elif word == "C":
  print("G")
else:
  print("C")

Solution (Python):
a = input()
if a == "A":
  print("T")
elif a == "T":
  print("A")
elif a == "G":
  print("C")
else:
  print("G")

Solution (Python):
b=input()
if b=="A":
	print("T")
if b=="T":
	print("A")
if b=="G":
	print("C")
if b=="C":
	print("G")

Solution (Python):
b = input()

if b == "A":
    print("T")
elif b == "T":
    print("A")
elif b == "C":
    print("G")
elif b == "G":
    print("C")

Solution (Python):
s = input()
t = []

for i in range(len(s)):
    if s[i] == "A":
        t.append("T")
        continue

    if s[i] == "T":
        t.append("A")
        continue

    if s[i] == "G":
        t.append("C")
        continue

    if s[i] == "C":
        t.append("G")
        continue

ans = "".join(t)
print(str(ans))

Solution (Python):
inp = input()
if inp == "A":
    print("T")
elif inp == "T":
    print("A")
elif inp == "C":
    print("G")
else:
    print("C")
print("\n")

Solution (Python):
b = input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'G':
    print("C")
else :
    print("G")

Solution (Python):
b=input()

if b=='A':
  print("T")
elif b=='T':
  print('A')
elif b=='C':
  print('G')
elif b=='G':
  print('C')

Solution (Python):
a = input()
ans = "error"
if a == "A":
    ans = "T"
elif a == "T":
    ans = "A"
elif a == "C":
    ans = "G"
elif a == "G":
    ans = "C"
print(ans)

Solution (Python):
a = input()

if a =="A":
	print("T")
elif a == "G":
	print("C")
elif a == "C":
	print("G")
elif a == "T":
	print("A")

Solution (Python):
s = input()

if s == "A":
    print("T")
elif s== "T":
    print("A")
elif s == "G":
    print("C")
else:
    print("G")

Solution (Python):


b = input()

if b == "A":
    print("T")
elif b == "T":
    print("A")
elif b == "C":
    print("G")
elif b == "G":
    print("C")

Solution (Python):


b = input()

if b == "A":
    print("T")
elif b == "C":
    print("G")
elif b == "G":
    print("C")
elif b == "T":
    print("A")

Solution (Python):
b = input()
if b=='A':
    print('T')
elif b=='T':
    print('A')
elif b=='C':
    print('G')
elif b=='G':
    print('C')

Solution (Python):
pairs = {'A': 'T', 'T': 'A', 'C': 'G', 'G': 'C'}
c = input()
print(pairs[c])

Solution (Python):
b = input()
if b == "A":
  print("T")
elif b == "T":
  print("A")
elif b == "G":
  print("C")
elif b == "C":
  print("G")

Solution (Python):
at = ['A', 'T']
cg = ['C', 'G']

b = input()

if b in at:
    at.remove(b)
    print(at[0])
else:
    cg.remove(b)
    print(cg[0])

Solution (Python):
moji = input()
if moji == "A" :
    print("T")
if moji == "C" :
    print("G")
if moji == "G" :
    print("C")
if moji == "T" :
    print("A")

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
elif b == 'G':
    print('C')

Solution (Python):
S = input()
if S == "A":
  print("T")
elif S =="T":
  print("A")
elif S=="C":
  print("G")
else:
  print("C")

Solution (Python):
d={"A":"T","T":"A","C":"G","G":"C"}

base=input()
print(d[base])

Solution (Python):
def main():
    b = input()

    if b == "A":
        print("T")
    elif b == "T":
        print("A")
    elif b == "G":
        print("C")
    else:
        print("G")
    return


if __name__ == '__main__':
    main()

Solution (Python):
import sys
import io
import math
import re

datalist = input().split()
data_a = str(datalist[0])

if data_a == 'A':
  print('T')
elif data_a == 'T':
  print('A')
elif data_a == 'C':
  print('G')
elif data_a == 'G':
  print('C')

Solution (Python):

input_val = str(input())

if input_val == "A":
  print("T")
elif input_val == "T":
  print("A")
elif input_val == "G":
  print("C")
elif input_val == "C":
  print("G")

Solution (Python):
b = input()
if b =='A':
    ans = 'T'
elif b == 'T':
    ans = 'A'
elif b == 'G':
    ans = 'C'
else:
    ans = 'G'
print(ans)

Solution (Python):
c = input()
m = {}
m['A'] = 'T'
m['T'] = 'A'
m['C'] = 'G'
m['G'] = 'C'
print(m[c])

Solution (Python):
import collections as c
ip = lambda : map(int, input().split())


d = {'A':'T','T':'A','C':'G','G':'C'}
b = input()
print(d[b])

Solution (Python):
s='ATACGC'
print(s[s.find(input())+1])

Solution (Python):
N = input()

if N == 'A':
    print('T')
elif N == 'T':
    print('A')
elif N == 'C':
    print('G')
elif N == 'G':
    print('C')

Solution (Python):
b = input()

if b ==	'A':
    print('T')
elif b == 'T':
    print('A')
elif b =='C':
    print('G')
elif b == 'G':
    print('C')

Solution (Python):
str = input()

if str == 'A':
  print('T')
elif str =='T':
  print('A')
elif str =='C':
  print('G')
elif str =='G':
  print('C')
else:
  print('error')

Solution (Python):
b=str(input())
ans="A"
if(b=="A"):
    ans="T"
elif(b=="C"):
    ans="G"
elif(b=="G"):
    ans="C"
print(ans)

Solution (Python):


b = input()

if b=='A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
else:
    print('C')

Solution (Python):
a = input()
if a=="A":
	a = "T"
elif a=="T":
	a = "A"
elif a=="G":
	a="C"
else:
	a="G"
print(a)

Solution (Python):


"""
Created on 2019/3/24
@author: shinjisu
"""




def getInt(): return int(input())
def getIntList(): return [int(x) for x in input().split()]

def getIntLines(n): return [int(input()) for i in range(n)]
def getIntMat(n, m):  
    
    mat = zeros2(n, m)
    for i in range(n):
        mat[i] = getIntList()
    return mat

def zeros(n): return [0]*n

def zeros2(n, m): return [zeros(m) for i in range(n)] 

ALPHABET = [chr(i+ord('a')) for i in range(26)]
DIGIT = [chr(i+ord('0')) for i in range(10)]
N1097 = 10**9 + 7
INF = 10**18

class Debug():
    def __init__(self):
        self.debug = True
 
    def off(self):
        self.debug = False
 
    def dmp(self, x, cmt=''):
        if self.debug:
            if cmt != '':
                print(cmt, ':  ', end='')
            print(x)
        return x


def prob():
    d = Debug()
    d.off()
    B = input()
    d.dmp((B), 'B')
    dic = {'A':'T', 'C':'G', 'G':'C', 'T':'A', }
    return dic[B]

ans = prob()
if ans is None:
    pass
elif type(ans) == tuple and ans[0] == 1:  
    for elm in ans[1]:
        print(elm)
else:
    print(ans)

Solution (Python):

def IL(): return list(map(int,input().split()))
def SL(): return input().split()
def I(): return int(input())
def S(): return list(input())
b=input()
if b=="A":
    print("T")
elif b=="T":
    print("A")
elif b=="G":
    print("C")
elif b=="C":
    print("G")

Solution (Python):
b = input()

if b == "A":
  b = b.replace("A","T")
  print(b)
  exit()
elif b == "T":
  b = b.replace("T","A")
  print(b)
  exit()
elif b == "G":
  b = b.replace("G","C")
  print(b)
  exit()
elif b == "C":
  b = b.replace("C","G")
  print(b)
  exit()

Solution (Python):
b = input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
else:
    print('C')

Solution (Python):
b = input()

if b == 'A':
    ans = 'T'
elif b == 'C':
    ans = 'G'
elif b == 'G':
    ans = 'C'
elif b == 'T':
    ans = 'A'

print(ans)

Solution (Python):
a = input()

if a == "A":
    print("T")
elif a == "C":
    print("G")
elif a == "G":
    print("C")
else:
    print("A")

Solution (Python):
b = input()

if b == "A":
	print("T")
elif b == "C":
	print("G")
elif b == "G":
	print("C")
else:
	print("A")

Solution (Python):
b =input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'G':
    print('C')
else:
    print('G')

Solution (Python):
b = input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'G':
    print('C')
elif b == 'C':
    print('G')

Solution (Python):
b = input()
be = b.replace('A', '&') 
bea = be.replace('T', 'A')
beam = bea.replace('&', 'T')
beami = beam.replace('C', '$')
beamin = beami.replace('G', 'C')
beaming = beamin.replace('$', 'G')
print(beaming)

Solution (Python):
a = input()
if a == "A":
  print("T")
elif a == "C":
  print("G")
elif a == "G":
  print("C")
else:
  print("A")

Solution (Python):
b = input()
if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
else:
    print('C')

Solution (Python):
b = input()
if b == 'A' or b == 'T':
    if b == 'A':
        print('T')
    else:
        print('A')
else:
    if b == 'C':
        print('G')
    else:
        print('C')

Solution (Python):
b=input()
ret=''
if b == 'A':
  ret = 'T'
elif b == 'C':
  ret = 'G'
elif b == 'T':
  ret = 'A'
else:
  ret = 'C'
print(ret)

Solution (Python):
i= input()

if i == 'A':
  print('T')
elif i == 'T':
  print('A')
elif i == 'C':
  print('G')
elif i == 'G':
  print('C')

Solution (Python):
s=input()
if s=="A":print("T")
elif s=="C":print("G")
elif s=="G":print("C")
else:print("A")

Solution (Python):
import sys

def main(inp):
    dna=list(next(inp))[0]
    
    if(dna=='A'):
        return "T"
    elif(dna=='T'):
        return "A"
    elif(dna=='C'):
        return "G"
    elif(dna=='G'):
        return "C"
      
print(main(sys.stdin))

Solution (Python):
print("ATCG"["TAGC".find(input())])

Solution (Python):
b = input()
l = ["A","T","C","G"]
if b == l[0]:
    print(l[1])
if b == l[1]:
    print(l[0])
if b == l[2]:
    print(l[3])
if b == l[3]:
    print(l[2])

Solution (Python):
b = str(input())

duble_helix = {
    'A': 'T',
    'C': 'G', 
    'G': 'C', 
    'T': 'A'
}

print(duble_helix[b])

Solution (Python):
S = list(input())

for i,q in enumerate(S):
    if q == 'A':
        S[i] = 'T'
    elif q == 'T':
        S[i] = 'A'
    elif q == 'G':
        S[i] = 'C'
    else:
        S[i] = 'G'
print("".join(S))

Solution (Python):
X=["A" if c == "T" else "T" if c == "A" else "G" if c == "C" else "C" for c in input()]

print("".join(X))

Solution (Python):
enki = input()

if enki == "A":
    print("T")
elif enki == "T":
    print("A")
elif enki == "C":
    print("G")
else:
    print("C")

Solution (Python):
b = input()
ans = ''
for i in range(len(b)):
    if b[i] == 'A':
        ans = ans + 'T' 
    elif b[i] == 'T':
        ans = ans + 'A'
    elif b[i] == 'G':
        ans = ans + 'C'
    elif b[i] == 'C':
        ans = ans + 'G'
        
print(ans)

Solution (Python):
word = input()
if word == "A":
  print("T")
elif word == "T":
  print("A")
elif word == "G":
  print("C")
elif word == "C":
  print("G")

Solution (Python):
l1 = ['A', 'C', 'G', 'T']
l2 = ['T', 'G', 'C', 'A']

s = input()
print(l2[l1.index(s)])

Solution (Python):
moji = input()

if moji == "A":
    print("T")
elif moji == "T":
    print("A")
elif moji == "G":
    print("C")
else:
    print("G")

exit()

Solution (Python):
i = input()
if i == "A":
    print("T")
if i == "C":
    print("G")
if i == "G":
    print("C")
if i == "T":
    print("A")

Solution (Python):
b = input()

for c in b:
  if c == 'A': print('T', end="")
  if c == 'T': print('A', end="")
  if c == 'G': print('C', end="")
  if c == 'C': print('G', end="")
print()

Solution (Python):
b = input()

if b == 'A':
    print('T')
elif b == 'T':
    print('A')
elif b == 'C':
    print('G')
elif b == 'G':
    print('C')

Solution (Python):

b = input()
if b == "A":
    print("T")
elif b == "T":
    print("A")
elif b == "C":
    print("G")
else:
    print("C")

Solution (Python):
s=input()
if s=='A':
    print('T')
if s=='T':
    print('A')
if s=='G':
    print('C')
if s=='C':
    print('G')

Solution (Python):
s=input()
if s=="A":
	print("T")
elif s=="C":
	print("G")
elif s=="T":
	print("A")
else:
	print("C")

Solution (Python):


i = input()


if i == 'A':
    print('T')
elif i == 'T':
    print('A')
elif i == 'C':
    print('G')
elif i == 'G':
    print('C')

Solution (Python):
b = str(input())

if b == "A" :
    print("T")
elif b == "C":
    print("G")
elif b == "G":
    print("C")
elif b == "T":
    print("A")
else:
    print("error")

Solution (Python):
x=input()
if x=="A":
    print("T")
elif x=="C":
    print("G")
elif x=="T":
    print("A")
else:
    print("C")

Solution (Python):
b=str(input())
if b=="A":
  print("T")
elif b=="T":
  print("A")
elif b=="G":
  print("C")
elif b=="C":
  print("G")

Solution (Python):
c = input()

if c == 'A':
    print('T')
elif c == 'T':
    print('A')
elif c == 'C':
    print('G')
elif c == 'G':
    print('C')

Solution (Python):
b = input()
if b == "A":
    print("T")
elif b == "C":
    print("G")
elif b == "G":
    print("C")
elif b == "T":
    print("A")

Solution (Python):
b = input()
if b == 'A':
  print('T')
elif b == 'T':
  print('A')
elif b == 'G':
  print('C')
elif b == 'C':
  print('G')

Solution (Python):
b = input()
if b == 'A':
    print('T')
elif b=='T':
    print('A')
elif b=='C':
    print('G')
elif b=='G':
    print('C')

Solution (Python):
input_text = input()
output_text = ''

if input_text == 'A':
  output_text = 'T'
elif input_text == 'C':
  output_text = 'G'
elif input_text == 'G':
  output_text = 'C'
else:
  output_text = 'A'
  
print(output_text)

Solution (Python):
pair = {'A': 'T', 'T':'A', 'C': 'G', 'G': 'C'}
b = raw_input()
print pair[b]

Solution (Python):
n = str(input())
if n == 'A':
    print('T')
elif n == 'C':
    print('G')
elif n == 'G':
    print('C')
else:
    print('A')

Solution (Python):
def main():
    b = {'A': 'T', 'T': 'A', 'G': 'C', 'C': 'G'}
    print(b[input()])


main()

Solution (Python):
gene = {x:y for x,y in zip("ATCG","TAGC")}
b = input()
print(gene[b])