'use strict'

function main(s) {

  const x = Number(s);

  let i = 0;
  let ans = 0;
  while (ans <= x) {
    i += 1;
    ans = i * i;
  }
  ans = (i - 1) * (i - 1);
  console.log(ans);
}

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