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 Java8 (OpenJDK 1.8.0) (judge verdict: Accepted)

import com.sun.org.apache.bcel.internal.generic.BIPUSH;

import java.io.PrintWriter;
import java.util.Scanner;

public class Main {
    static Scanner sc = new Scanner(System.in);
    static PrintWriter out = new PrintWriter(System.out);

    public static final void NO() { out.println("NO"); }
    public static final void YES() { out.println("YES"); }

    public static final void main(String[] args) {
        new Main().solve();
        out.flush();
    }

    // ========================================================================= //

    public void solve() {
        long N = sc.nextInt();
        long sqrt = (long)Math.ceil(Math.sqrt(N));
        while (sqrt * sqrt > N) {
            sqrt--;
        }
        System.out.println(sqrt * sqrt);
    }

}