# Created by: Chris Asante
# Created on: 19-March-2019
# Created for: ICS3U
# Daily Assignment – Unit 3-07  n n
# This program is an application that calculates the diameter of a pizza

input = input()
test = int(input)
answer = 1
for i in range(test):
    answer = (i+1)*answer
    
    
print (answer)