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: Wrong Answer)

import java.util.*;
import java.util.Collections;

public class Main {

  public static void main(String[] args) {
    Scanner sc = new Scanner(System.in);
    long A = sc.nextInt();
    System.out.println((long) Math.floor(Math.sqrt(A)) * Math.floor(Math.sqrt(A)));
  }

  public static void primeFactorization(int num) {
    int Z = 0;
    for (int i = 2; num > i; i++) {
      while (num % i == 0) {
        System.out.println(i);
        num /= i;
        Z = num;
      }
    }
    System.out.println(Z);
  }

  public static boolean isPrime(int num) {
    if (num < 2)
      return false;
    else if (num == 2)
      return true;
    else if (num % 2 == 0)
      return false;

    for (int i = 3; i < num; i += 2) {
      if (num % i == 0) {
        return false;
      }
    }
    return true;
  }
}