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 Go (1.6) (judge verdict: Accepted)

package main

import (
	"fmt"
	"sort"
)

var m map[int]int

func main() {
	var N int
	fmt.Scan(&N)
	var arr []int
	for i := 1; i*i <= N; i++ {
		arr = append(arr, i*i)
	}
	sort.Sort(sort.Reverse(sort.IntSlice(arr)))
	for i := 0; i < len(arr); i++ {
		if N >= arr[i] {
			fmt.Println(arr[i])
			return
		}
	}
}