#!/bin/python3

import math
import os
import random
import re
import sys

# Complete the extraLongFactorials function below.
def extraLongFactorials(n):
    cache = {}
    def rec(n):
        if n in cache:
            return cache[n]
        if n == 1:
            return 1
        result = n * rec(n-1)
        cache[n] = result
        return result
    return rec(n)

if __name__ == '__main__':
    n = int(input())

    print(extraLongFactorials(n))