fn main() {
    input!{
		n: usize,
	}

	// 約数個数が奇数個の値を数え上げる
	// 2乗根、4乗根、6乗根、、、となるが、4乗,6乗根の値は2乗根に含む。
	// 従って2乗根の個数だけを数え上げればよい。

	let mut ok = 1usize;
	let mut ng = 1_000_000_000 + 9;

	for _ in 0..40 {
		let mid = (ok + ng) / 2;
		if mid * mid <= n {
			ok = mid;
		}
		else {
			ng = mid;
		}
	}
	println!("{}", ok);
}

// const MOD17: usize = 1000000007;
// const MOD93: usize = 998244353;
// const INF: usize = 1 << 60;
// let dx = vec![!0, 0, 1, 0]; // 上左下右
// let dy = vec![0, !0, 0, 1]; // 上左下右
// let d = vec!{(!0, 0), (0, !0), (1, 0), (0, 1)}; // 上左下右

#[allow(unused)]
use proconio::{input, marker::Chars, marker::Usize1};

#[allow(unused)]
use std::{
	mem::swap,
	cmp::min, cmp::max,
	cmp::Reverse,
	collections::HashSet, collections::BTreeSet,
	collections::HashMap, collections::BTreeMap,
	collections::BinaryHeap,
	collections::VecDeque,
	iter::FromIterator,
};