/*
	Counting number of digits of n! (base 10)
	@Author: md.moniruzzaman
*/

#include<stdio.h>
#include<math.h>

int countDigit(int n) {
	int  i;
	double count = 0;
	for(i = 1; i<= n; i++) {
		
		count += log10(i);
	}
	return (int)count+1;
}
void main() {
	int n;
	scanf("%d",&n);
	printf("%d\n",countDigit(n));

}