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 C# (Mono 4.6.2.0) (judge verdict: Accepted)

using System;
using System.Collections;
using System.Collections.Generic;
using System.Linq;

class Magatro
{
    public void Solve()
    {
        var N = int.Parse(Console.ReadLine());
        int ans = 0;
        for (int i = 1; i * i <= N; i++)
        {
            ans = i * i;
        }
        Console.WriteLine(ans.ToString());
    }
    static void Main(string[] args)
    {
        new Magatro().Solve();
    }
}