#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: linmiaoling
	Language: C++
	Result: Accepted
	Time:21 ms
	Memory:2072 kb
****************************************************************/