#include<stdio.h>   

int main(){ 
	int n,i,sum=1;
	scanf("%d",&n);
	
	
	for(i = 1;i <= n;i++){ 
		sum *= i;  //等同于 sum = sum * i； 
	}
	
	printf("%d",sum);
	return 0;
} 
/**************************************************************
	Problem: 1004
	User: admin
	Language: C
	Result: Accepted
	Time:10 ms
	Memory:1144 kb
****************************************************************/