import Foundation

var btl = readLine()!.components(separatedBy:" ").map{Int($0)!}
while(btl[0] > 0 || btl[2] > 0){
  btl[2] -= btl[1]
  btl[0] -= btl[3]
}
if(btl[2] = 0){
  print("Yes")
}else{
  print("No")
}