#include<stdio.h>
int main()
{
	int num;
	
	scanf("%d",&num);
	while (num<=0)
	{
		
		scanf("%d",&num);
	}
	int Sum=1;
	for(int i=1;i<=num;i++)
	{
		Sum=Sum*i;

	}
	printf("%d",Sum);
return 0;
}