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;

namespace MyProgram
{
    public class Program
    {	
        public static void Main(string[] args)
        {
            double N = double.Parse(Console.ReadLine());
            double a = 1;
            
            while(true)
            {
                if(Math.Pow(a+1,2) > N)
                {
                    break;
                }
                else
                {
                    a++;
                }
            }
            Console.WriteLine(Math.Pow(a,2));
        }
    }
}