C++ :

#include <iostream>
using namespace std;

int main(){
	int c = 1;	
	double t = 2,s = 2,x;
	cin>>x;
	while(s < x){
		t = t * 0.98;
		s = s + t;
		c++;
	}
	
	cout<<c<<endl;
}

Java :

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
//        int num1 = scanner.nextInt();
//        int num2 = scanner.nextInt();
//        int num3 = scanner.nextInt();
//        int num4 = scanner.nextInt();
//        int num5 = scanner.nextInt();

        double num1 = scanner.nextDouble();
//        double num2 = scanner.nextDouble();
//        double num3 = scanner.nextDouble();
        int m = 0;
        double x = 2.0;
//        int a, b, c, d, m, count = 0;
        while(num1>0)
        {
            num1-=x;
            x*=0.98;
            m++;
        }
        System.out.println(m);
        }
}

Python :

n = float(input())
i = 0
a = 2
b = 0
while(b < n):
    b += a
    a *= 0.98
    i += 1
print(i)