#include <bits/stdc++.h>
using namespace std;
int main(){
    double n,o=2,z;
    cin>>n;
    for(int i=1;n>=0;i++){
    	n-=o;
    	o*=0.98;
    	z++;
    }
    cout<<z; 
} 
/**************************************************************
	Problem: 1460
	User: wangyiyang
	Language: C++
	Result: Accepted
	Time:26 ms
	Memory:2072 kb
****************************************************************/