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: Wrong Answer)

// contest.go
package main

import (
	"bufio"
	"fmt"
	"os"
	"strconv"
)

var sc = bufio.NewScanner(os.Stdin)

func main() {
	var n int
	n = nextInt()
	var d int
	d = sqr(n)
	fmt.Println(d)

}
func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}
func nextLine() string {
	sc.Scan()
	return sc.Text()
}

func sqr(n int) int {
	var a int
	var d int
	d = n
	for i := n; i != (d * d); i-- {
		for d = 1; i != (d * d); d++ {
			a = i
			if d*d >= i {
				break
			}
		}
		if i == (d * d) {
			a = i
			break
		}
		if i < 0 {
			break
		}
	}
	return a
}