import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    }
} import java.util.*; util.* java public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    }
} Main public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    } main {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    } Scanner sc = new Scanner(System.in); sc new Scanner(System.in) int A = sc.nextInt(); A sc.nextInt() sc.nextInt sc int B = sc.nextInt(); B sc.nextInt() sc.nextInt sc int C = sc.nextInt(); C sc.nextInt() sc.nextInt sc int D = sc.nextInt(); D sc.nextInt() sc.nextInt sc boolean flg = false; flg false while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        } true {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        } C = C - B C C - B C B if (C <= 0) {
                flg = true;
                break;
            } C <= 0 C 0 {
                flg = true;
                break;
            } flg = true flg true break; A = A - D A A - D A D if (A <= 0) {
                break;
            } A <= 0 A 0 {
                break;
            } break; if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        } flg {
            System.out.println("Yes");
        } System.out.println("Yes") System.out.println System.out System System.out "Yes" {
            System.out.println("No");
        } System.out.println("No") System.out.println System.out System System.out "No" String[] args args public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    }
} public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    }
} Main
import java.util.*;

public class Main {
    public static void main(String[] args) throws Exception {
        // Your code here!
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int C = sc.nextInt();
        int D = sc.nextInt();
        
        boolean flg = false;
        while (true) {
            
            C = C - B;
            if (C <= 0) {
                flg = true;
                break;
            }
            
            A = A - D;
            if (A <= 0) {
                break;
            } 
        }
        
        if (flg) {
            System.out.println("Yes");
        } else {
            System.out.println("No");
        }
        
    }
}
