#include<bits/stdc++.h>
using namespace std;

int main()
{
	long double n,a=2;
	cin>>n;
	int sum=0;
	while(n>0)
	{
		n=n-a;
		a=a*0.98;
		sum+=1;
	}
	cout<<sum<<endl;
	return 0;
}