#include <iostream>
#include <cmath>
#include <cstdio>
using namespace std;

double s=0.0;
int ans=0,x=0;
int main(){
	scanf("%d",s);
	while(s){
		s-=2*pow(0.98,x);
		ans++,x++;
	}
	printf("%d",ans);
	return 0;
}

全部WA了，求大佬讲解！rt