#include<iostream>
#include<cmath>
using namespace std;
int main()
{
	float s;
	cin >> s;
	float a=0.0;
	for (int i = 0; i < 100; i++) {
		a = a + pow(0.98, i);
		if (a >= s) {		
			break;
			cout << i;
		}
	}
	return 0;
}