sekvence = "ATTCGTAGCTAGCATGCATCGA"
ksekvence = ""
baze = {"A": "T", "C": "G", "G": "C", "T": "A"}
for i in range(len(sekvence)):
    ##################      klic      #
    ksekvence += baze[ sekvence[-i-1] ]

print(sekvence)
print(ksekvence)