Problem:
Score : 200 points

Problem Statement

Find the largest square number not exceeding N. Here, a square number is an integer that can be represented as the square of an integer.

Constraints

1 \leq N \leq 10^9

N is an integer.

Input

Input is given from Standard Input in the following format:

N

Output

Print the largest square number not exceeding N.

Sample Input 1

10

Sample Output 1

9

10 is not square, but 9 = 3 × 3 is. Thus, we print 9.

Sample Input 2

81

Sample Output 2

81

Sample Input 3

271828182

Sample Output 3

271821169

Solution in Rust (1.15.1) (judge verdict: Accepted)

use std::io;

fn main() {
    let N=get_int();
    let mut max = 2;
    while N>=max*max {
        max+=1;
    }
    println!("{}",(max-1)*(max-1));
}

fn get_String()->String{
    let mut s =String::new();
    io::stdin().read_line(&mut s).expect("Fail!");        
    s.trim().to_string()
}

fn get_int()->i32{
    let mut input =String::new();
    io::stdin().read_line(&mut input).expect("Fail!");
    input.trim().to_string().parse().unwrap()
}