#include<bits/stdc++.h>
using namespace std;
int main(){
	int s = 0,cnt = 0,cnt1 = 0,ans = 1;
	cin >> s;
	cnt = 2;
	cnt1 = cnt * 0.98;
	while(cnt < s){
		cnt += cnt1;
		cnt1 *= 0.98;
		ans ++;
	}
	cout << ans;
	return 0;
}