/*
 * number of digits in n!
 */
#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>

int
digs (unsigned long int N);

int
main (void)
{
	unsigned long int N;
	char s [100];

	while (gets (s) != NULL) {
		sscanf (s, "%lu", &N);
		printf ("%d\n", digs (N));
	}

	return 0;
}

int
digs (unsigned long int N)
{
	unsigned long int i;
	double ans;

	ans = 0.0;

	for (i = N; i > 0; i--) {
		ans += log (i) / log (10);
	}

	return (1 + (int)(floor (ans)));
}