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 JavaScript (node.js v5.12) (judge verdict: Runtime Error)

function search(num) {
  const sqrt = Math.sqrt(num);
  if (Number.isInteger(sqrt)) {
    return num;
  } else {
    return search(num - 1);
  }
}

function main(input) {
  const result = search(Number(input))
  console.log(result);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'))