#include<bits/stdc++.h>
using namespace std;
int c;
double m,sum;
int main()
{
    cin>>m;
    int n=2;
    while(true)
    {
    	if(sum>=m)
    		break;
        sum+=n;
        n*=0.98;
        c+=1;
    }
    cout<<c<<endl;
}