Code:
#!/bin/python3
import math
import os
import random
import re
import sys
# Complete the factorial function below.
def factorial(n):
for i in range (1, n):
n= n*i
return n
if __name__ == '__main__':
fptr = open(os.environ['OUTPUT_PATH'], 'w')
n = int(input())
result = factorial(n)
fptr.write(str(result) + '\n')
fptr.close()