#include <iostream>
using namespace std;

int main()
{
    double s;
    cin >> s;
    int cnt = 0;
    double sum = 0.0;
    double len = 2.0;

    while (sum < s)
    {
        sum += len;
        cnt++;
        len *= 0.98;
    }
    cout << cnt << endl;
    return 0;
}