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;

class Program {
    static void Main(string[] args) {
        int n = Cin.Ni();

        for (int i = n; i > 0; i--) {
            int sqrt = (int)Math.Sqrt(i);
            if (sqrt * sqrt == i) {
                Console.WriteLine(i);
                return;
            }
        }


    }
}


public class Cin {
    private static string[] s = new string[0];
    private static int i = 0;

    private static char[] cs = new char[] { ' ' };

    public static string Next() {
        if (i < s.Length) return s[i++];
        string st = Console.ReadLine();
        while (st == "") st = Console.ReadLine();
        s = st.Split(cs, StringSplitOptions.RemoveEmptyEntries);
        i = 0;
        return Next();
    }

    public static int Ni() {
        return int.Parse(Next());
    }

    public static long NextLong() {
        return long.Parse(Next());
    }

    public static double NextDouble() {
        return double.Parse(Next());
    }

}