"use strict";

const input = require("fs").readFileSync("/dev/stdin", "utf8").trim();

const inputs = input.split("\n").map(i => +i);

const exec = (inputs) => {
  const k = inputs.pop();

  const yay = (inputs[inputs.length-1] - inputs[0]) <= k;

  console.log(yay ? "Yay!" : ":(");
}

exec(inputs);
