#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <iomanip>
using namespace std;
int main(void){
	int count=0;
	double a;
	double b=2;
	scanf("%fl",&a);
	while(a>0){
		a=a-b;
		b = b*0.98;
		count++;
	}
	printf("%d",count);
    return 0;
}