#include<iostream>
using namespace std;
int main() {double s;cin >> s;int n = 0;double sum = 0;double k = 2;while (sum < s) {sum += k;n++;k *= 0.98;}cout << n << endl;return 0;
}
#include<iostream>
using namespace std;
int main() {double s;cin >> s;int n = 0;double sum = 0;double k = 2;while (sum < s) {sum += k;n++;k *= 0.98;}cout << n << endl;return 0;
}