6

#include<bits/stdc++.h>
using namespace std;
int main()
{
double x,k=2,t=0,s=0;
cin>>x;
while(1)
{
s=s+k;
k=k*0.98;
t++;
if(s>=x)
{
break;
}
}
cout<<t;
return 0;
}