sales.py

# Start
n = 0
p = 10
while not (n >= 1 and n < 26):
    n = input("How many tickets? ")
    n = int(n)
    if not (n >= 1 and n < 26):
        print("Number must between 1 to 25!, Pls try again!")

if n < 10:
    d = 0
elif n >= 10 and n < 20:
    d = 0.1
else:
    d = 0.2

cost = n * (1 - d) * p
print(f"Total cost for {n} tickets is {cost}")
# End