function fact (n)
if n == 0 then
return 1
else
return n * fact(n-1)
end
end
print("enter a number:")
a = io.read("*number")
print(fact(a))
ZnVuY3Rpb24gZmFjdCAobikKICAgICAgaWYgbiA9PSAwIHRoZW4KICAgICAgICByZXR1cm4gMQogICAgICBlbHNlCiAgICAgICAgcmV0dXJuIG4gKiBmYWN0KG4tMSkKICAgICAgZW5kCiAgICBlbmQKICAgIAogICAgcHJpbnQoImVudGVyIGEgbnVtYmVyOiIpCiAgICBhID0gaW8ucmVhZCgiKm51bWJlciIpIAogICAgcHJpbnQoZmFjdChhKSk=