hdu 4950

#include<stdio.h>
int main(){
     __int64 h,a,b,k,j=0;
     while(scanf("%I64d%I64d%I64d%I64d",&h,&a,&b,&k),h||a||b||k) {
        printf("Case #%I64d: ",++j);
        if(h<a+1) {
            printf("YES\n");
            continue;
        }
        if(a<=b) {
            printf("NO\n");
            continue;
        }
        if((a-b)*k-b>0) {
            printf("YES\n");
            continue;
        }
        if(h-(a-b)*(k-1)-a<1) {
            printf("YES\n");
            continue;
        }
        printf("NO\n");
     }
return 0;
}