let moves attack defence =
  defence / attack + (if defence mod attack == 0 then 0 else 1)

let () =
  let a = read_int() in
  let b = read_int() in
  let c = read_int() in
  let d = read_int() in
  let s1 = moves (min c d) (max a b) in
  let s2 = moves (min a b) (max c d) in
  print_string (if s1 <= s2 then "Yes" else "No")