import jeliot.io.*;
// 
// this is an example on 
// how to use Jeliot with eScanner
// with the names Jeliot uses 
// import java.util.Scanner;
class Example {
   
   public  static void main() {
        java.util.Scanner Input = new java.util.Scanner(System.in);     
        int x = Input.nextInt();
        double real = 20;
        int i = 0;
        while ( real > x) {
            real = real * 0.4;
            i = i + 1;
           System.out.println(i);
        }
        
    }
}