use std::io::Read;

fn main() {
    let mut buf = String::new();
    std::io::stdin().read_to_string(&mut buf).unwrap();
    
    let n: usize = buf.trim().parse().unwrap();
    let mut count: usize = 0;
    let mut pow_2: usize = 1;
    
    while pow_2 < n {
        pow_2 <<= 1;
        count += 1;
    }
    
    println!("{}", count);
}