function Main(input)
{
	input = input.split("\n")

  var a = parseInt(input[0], 10)

  var b = 0
  var result = 0

  while(a > result)
  {
    b = b + 1

    result = b * b
  }

  if (result > a)
  {
    b = b - 1
    result = b * b
  }


  console.log(result);

}

Main(require("fs").readFileSync("/dev/stdin", "utf8"))
