#include <stdio.h>
int main(void)
{
    int a, b, c, d;

    scanf_s("%d %d %d %d", &a, &b, &c, &d);

    while(1)
    {
        c = c - b;
        if(c == 0)
        {
            printf("Yes");
            break;
        }
        a = a - d;
        if(a == 0)
        {
            printf("No");
            break;
        }
    }

}