#include<iostream>
#include<algorithm>
using namespace std;
int main(){
	double a;
	cin>>a;
	double gg = 2.0,sum = 0;
	int i = 0;
	while(sum > a or sum == a){
		if(i == 0){
			sum += gg;
			i ++;
		}
		else{
			sum += (gg * 100/98);
			i ++;
		}	
	}
	cout<<i;
}