#include<stdio.h>
#include<math.h>
double l,d,x,y;
double ff(double n)
{
    double x0,y0,c,s;
    s=sin(n);
    c=cos(n);
    x0=-1*(d/s+c*l);
    y0=(d/c+s*l);
    double tmp=(1.0-x/y0)*x0*(-1);
    return tmp;
}

int main()
{
    double left,right,mid1,mid2,max;
    while(scanf("%lf%lf%lf%lf",&x,&y,&l,&d)!=EOF)
        {
            left=0;
            right=asin(1.0);
            max=0;
            while(fabs(right-left)>=0.000001)
                {
                    mid1=(right+left)/2;
                    mid2=(left+mid1)/2;
                    if(ff(mid1)>ff(mid2))
                        {
                            left=mid2;
                        }
                    else
                        {
                            right=mid1;
                        }
                }
            double tmp=ff(left);
            if(tmp<y)printf("yes\n");
            else printf("no\n");
        }
    return 0;
}