import algorithm, macros, math, sequtils, strutils, tables
# import bitops, lenientops, deques,
#   heapqueue, sets, sugar

let read* = iterator: string =
  while true: (for s in stdin.readLine.split: yield s)

template input*(T: static[typedesc]): untyped = 
  when T is int: read().parseInt
  elif T is float: read().parseFloat
  elif T is string: read()
  elif T is char: read()[0]

macro dump*(args: varargs[typed]): untyped =
  result = newNimNode(nnkStmtList)
  for x in args:
    let s = toStrLit(x)
    result.add quote do: stderr.write `s`, " = ", `x`, " "
  result.add quote do: stderr.write "\n"

proc `|=`*(n: var int, m: int) = n = n or m
proc `|=`*(n: var bool, m: bool) = n = n or m
proc `&=`*(n: var int, m: int) = n = n and m
proc `&=`*(n: var bool, m: bool) = n = n and m
proc `^=`*(n: var int, m: int) = n = n xor m
proc `^=`*(n: var bool, m: bool) = n = n xor m
proc `%=`*(n: var int, m: int) = n = n mod m
proc `/=`*(n: var int, m: int) = n = n div m
proc `<<=`*(n: var int, m: int) = n = n shl m
proc `>>=`*(n: var int, m: int) = n = n shr m
proc `<?=`*(n: var SomeNumber, m: SomeNumber) = n = min(n, m)
proc `>?=`*(n: var SomeNumber, m: SomeNumber) = n = max(n, m)
proc newSeq2*[T](n1, n2: Natural): seq[seq[T]] = newSeqWith(n1, newSeq[T](n2))
proc newSeq3*[T](n1, n2, n3: Natural): seq[seq[seq[T]]] = newSeqWith(n1, newSeqWith(n2, newSeq[T](n3)))
proc newSeq4*[T](n1, n2, n3, n4: Natural): seq[seq[seq[seq[T]]]] = newSeqWith(n1, newSeqWith(n2, newSeqWith(n3, newSeq[T](n4))))

# -------------------------------------------------- #

let L, R, M, K = input(int)
var min, max: int
if R - L + 1 >= M:
  min = 0
  max = M - 1
else:
  let modL = L mod M
  let modR = R mod M
  if modL < modR:
    min = modL
    max = modR
  else:
    min = 0
    max = M - 1
let sumMin = min * K
let sumMax = max * K
if sumMax - sumMin + 1 >= M:
  echo "Yes"
elif (sumMax mod M) < (sumMin mod M):
  echo "Yes"
elif sumMin mod M == 0:
  echo "Yes"
else:
  echo "No"