if(one>two)
  {
  var a = one;
  }
  else
  {
  var a = two;
  }

if(three>four)
  {
  var b = three;
  }
  else
  {
  var b = four;
  }

if(a>b)
  {
  alert("The greatest number is " + a)
  }
else if(b>a)
  {
  alert("The greatest number is " + b)
  }
}