#include<bits/stdc++.h>
using namespace std;
int swim_time = 0;
long double swim_m, one_m = 2, swimed_m = 0;
int main()
{
    cin >> swim_m;
    while (swimed_m > swim_m)
    {
        swimed_m += one_m;
        one_m = one_m / 100 * 98;
        swim_time++;
    }
    cout << swim_time << endl;
    return 0;
}