#include <bits/stdc++.h>
using namespace std;
int main()
{
    long long n;
    cin>>n;
    unsigned long long tong=2;
    int dem=0;
    while(tong<=n)
        {
            tong=tong*2;
            dem++;
        }
    cout<<dem;
    return 0;
}

#include <bits/stdc++.h>
using namespace std;
int main() {
    long long n, t = 2;
    int d=0;
    cin>>n;
    while ((t*= 2)<=n) ++d;
    cout<<d;
    return 0;
}