/*
 * factorial.c
 *
 *  Created on: Feb 23, 2012
 *      Author: Andrei
 */
#include <stdio.h>

int main(void)
{
	FILE *in;
	in=fopen("fact.in","r");
	FILE *out;
	out=fopen("fact.out","w");
	long n,p;
	fscanf (in, "%d", &p);
	if (p==0)
		n=1;
	else if (p%2==0)
		n=p/2*10;
	else n=p*5;
	fprintf (out, "%d", n);
	fclose(in);
	fclose(out);
	return 0;
}