/*
 *  factorial.c
 *  
 *
 *  Created by Andrew on 2/5/11.
 *  Copyright 2011 UvA. All rights reserved.
 *
 */

//5!=5*4*3*2*1;

extern void printInt(int i);
extern int scanInt();
int fac(int num)
{
	int input=num;
	int output=1;
	int i=1;
	
	if(input==0)
		output=1;
	else 
	{
		while(i<=input)
		{
			output=output*i;
			i=i+1;
		}
	}
	return output;
}

export int main()
{
	int N=scanInt();
	int output=	fac(N);	
	printInt(output);
	return 0;	
}