use fio::*;

fn main() {
    let n = read::<usize>();

    let isqrt = |n: usize| {
        let mut lo = 1;
        let mut hi = n + 1;
        while lo + 1 != hi {
            let mi = (lo + hi) / 2;
            if mi.saturating_mul(mi) <= n {
                lo = mi;
            } else {
                hi = mi;
            }
        }
        lo
    };

    let x = isqrt(n);

    if n / x == x {
        println!("{}", 2 * x - 1);
    } else {
        println!("{}", 2 * x);
    }
}

mod fio {
    use std::{
        cell::RefCell,
        fmt::Debug,
        io::{BufWriter, StdinLock, StdoutLock, stdin, stdout},
        str::FromStr,
    };
    thread_local! {
        pub static STDIN: RefCell<StdinLock<'static>> = RefCell::new(stdin().lock());
        pub static STDOUT: RefCell<BufWriter<StdoutLock<'static>>> = RefCell::new(BufWriter::new(stdout().lock()));
    }

    #[allow(dead_code)]
    pub fn read<T: FromStr>() -> T
    where
        <T as FromStr>::Err: Debug,
    {
        read_line().parse().unwrap()
    }

    #[allow(dead_code)]
    pub fn read_vec<T: FromStr>() -> Vec<T>
    where
        <T as FromStr>::Err: Debug,
    {
        read_line()
            .split_whitespace()
            .map(|x| x.parse().unwrap())
            .collect()
    }

    #[allow(dead_code)]
    pub fn read_tuple<T: FromStr, const N: usize>() -> [T; N]
    where
        T: Debug,
        <T as FromStr>::Err: Debug,
    {
        read_vec::<T>().try_into().unwrap()
    }

    pub fn read_line() -> String {
        use std::io::BufRead;
        let mut s = String::new();
        STDIN.with(|cell| {
            cell.borrow_mut().read_line(&mut s).unwrap();
        });
        String::from_str(s.trim_end()).unwrap()
    }
}

#[macro_export]
macro_rules! print {
($($t:tt)*) => {
    use std::io::Write;
    use fio::STDOUT;
    STDOUT.with(|cell| write!(cell.borrow_mut(), $($t)*).unwrap())
};
}

#[macro_export]
macro_rules! println {
($($t:tt)*) => {
    use std::io::Write;
    use fio::STDOUT;
    STDOUT.with(|cell| writeln!(cell.borrow_mut(), $($t)*).unwrap())
};
}