'use strict'
function Main(input){
  input=input.trim().split(/\s+/).map(x=>x-0);
  var k=input.pop();
  var result=(input.pop()-input.shift()<=k);
  var ans=result?'Yay!':':(';
  console.log(ans);
}

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