def leapyear():

while True:

y=input("Enter year: ")

try:

year = int(y)

if year%4 == 0:

if year%100 == 0:

if year%400 == 0:

print("Leap year!")

break

else:

print("NOT a leap year")

continue

except:

print("Error, please check input")

continue

print("End")