import java.util.Scanner;

public class Main {

public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    //定义变量接受要游的距离
    double distance = sc.nextDouble();

    //定义变量接受要游的步数,还有步幅
    int steps = 0;
    double stepLength = 2;

    //用while循环来计算步数
    while (distance > 0) {
        distance -= stepLength;
        steps++;
        stepLength *= 0.98;
    }

    //输出步数
    System.out.println(steps);
}

}