//package atcoder;
 
import java.util.*;
 
public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	}
} import java.util.*; util.* java public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	}
} Main public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	} main {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	} Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A[] = new int[4]; A new int[4] 4 for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		} int i=0; int i=0; i 0 i<4 i 4 i++ i++ i {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		} {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		} A[i] = sc.nextInt() A[i] A i sc.nextInt() sc.nextInt sc while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		} A[0]>0||A[2]>0 A[0]>0 A[0] A 0 0 A[2]>0 A[2] A 2 0 {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		} A[2] = A[2]-A[1] A[2] A 2 A[2]-A[1] A[2] A 2 A[1] A 1 if(A[2]<=0) {
				System.out.println("Yes");
				break;
			} A[2]<=0 A[2] A 2 0 {
				System.out.println("Yes");
				break;
			} System.out.println("Yes") System.out.println System.out System System.out "Yes" break; A[0] = A[0]-A[3] A[0] A 0 A[0]-A[3] A[0] A 0 A[3] A 3 if(A[0]<=0) {
				System.out.println("No");
				break;
			} A[0]<=0 A[0] A 0 0 {
				System.out.println("No");
				break;
			} System.out.println("No") System.out.println System.out System System.out "No" break; String[] args args public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	}
} public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	}
} Main
//package atcoder;
 
import java.util.*;
 
public class Main{
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int A[] = new int[4];
		for(int i=0;i<4;i++) {
			A[i] = sc.nextInt();
			//System.out.println(A[i]);
		}
		
		while(A[0]>0||A[2]>0) {
			A[2] = A[2]-A[1];
			//System.out.println(A[2]);
			if(A[2]<=0) {
				System.out.println("Yes");
				break;
			}
			A[0] = A[0]-A[3];
			if(A[0]<=0) {
				System.out.println("No");
				break;
			}
			
		}
	}
}
