import java.util.Scanner;
 
public class Main{
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int numa = scan.nextInt();
        int numb = scan.nextInt();
        int numc = scan.nextInt();
        int numd = scan.nextInt(); 
        int i;
        for(i=0;i<10000;i++){
            if(i%2 == 0){
                if(numc>0){
                    numc = numc - numb;}
                else{
                    System.out.println("Yes");
                    break;}
                }
            else{
                if(numa>0){
                    numa = numa - numd;}
                else{
                    System.out.println("No");
                    break;}
                }        
          }        
        scan.close();
    }
}
/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz