#![allow(dead_code, unused_imports, unused_macros, non_snake_case)]
use proconio::{
    input,
    marker::{Bytes, Chars, Usize1},
};

fn main() {
    input! {
        n: i64
    }

    println!("{}", sqrt_floor(n));
}

pub fn sqrt_floor(x: i64) -> i64 {
    let c = (64 - x.leading_zeros() + 1) / 2;
    let mut v = if c < 32 { 1 << c } else { 3_037_000_499 };
    while v * v > x {
        v = (v + x / v) / 2;
    }
    v
}