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

fn main() {
    input! {
        n: i64,
    }
    let mut left = 0;
    let mut right = n as i128 + 1;
    while (right - left).abs() > 1 {
        let mid = (right + left) / 2;
        if mid * mid > n as i128 {
            right = mid;
        } else {
            left = mid;
        }
    }
    println!("{}", left as i64)
}