def ZasifrujZnak (znak,a,b):
    abeceda = ["A","B","C","D","E","F","G","H","I","J","K","L","M","N","O","P","R","Q","S","T","U","V","W","X","Y","Z"]
    znakcislo = abeceda.index(znak)
    znak_cislo_sifra = (a*znakcislo+b)%26
    zasifrovanyznak=abeceda[znak_cislo_sifra]
    return zasifrovanyznak


znakOT = "D"
a = 7
b = 5
z = []

text = "AHOJ PEPO"

text = text.replace(" ","XMEZERAX")

text = text.replace("Ě","E")
text = text.replace("Š","S")
text = text.replace("Č","C")
text = text.replace("Ř","R")
text = text.replace("Ž","Z")
text = text.replace("Ý","Y")
text = text.replace("Á","A")
text = text.replace("Í","I")
text = text.replace("É","E")
text = text.replace("Ť","T")
text = text.replace("Ď","D")
text = text.replace("Ň","N")
text = text.replace("Ú","U")
text = text.replace("Ů","U")


text = text.replace("0","XYA")
text = text.replace("1","XYB")
text = text.replace("2","XYC")
text = text.replace("3","XYD")
text = text.replace("4","XYE")
text = text.replace("5","XYF")
text = text.replace("6","XYG")
text = text.replace("7","XYH")
text = text.replace("8","XYI")
text = text.replace("9","XYJ")

p = []

for i in range(0, len(text)):
    znakST = ZasifrujZnak(text[i], a, b)
    z.append(znakST)
p = "" .join(z)
print(p)