package backjoon;

// https://www.acmicpc.net/problem/10872

// 팩토리얼

import java.io.BufferedReader;

import java.io.IOException;

import java.io.InputStreamReader;

public class _10872 {

public static void main(String[] args) throws IOException {

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

int N = Integer.parseInt(br.readLine());

// sol1 반복문 사용

// memory 11452 runtime 76

/*

int fac = 1;

for(int i=1; i<=N; i++){

fac *= i;

}

System.out.println(fac);

*/

// sol2 재귀사용

// memory 11480 runtime 76

int sum = factorial(N);

System.out.println(sum);

}

public static int factorial(int n){

if(n <= 1) return 1;

return n * factorial(n-1);

}

}

/*

input

10

output

3628800

*/