# include <iostream>
using namespace std;

int main()
{
    double n, sum = 0, x = 2;
    int ans = 0;
    cin >> n;
    while (sum <= n)
    {
        sum += x;
        x *= 0.98;
        ans++;
    }
    if (sum == n) cout << ans << endl;
    else cout << ans + 1 << endl;
    return 0;
}

得了零分，不知道问题在哪