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);
}

}

#include<bits/stdc++.h>
double x;
using namespace std;
int main()
{
    cin>>x;
    cout<<ceil(log(1-x/100)/log(0.98));
    return 0;
}

#include<stdio.h>
int main()
{
    float a;
    double b=2;
    double c=2;
    int count=1;
    scanf("%f",&a);
    if(a>=b){
    while(b<=a){
        c=c*0.98;
        b=b+c;
        count++;
    }
    printf("%d",count);
    }else if(a<b){
    printf("1");
    }
    return 0;
}