#include<stdio.h>
int main()
{
    char a,b,c,d,e,f;
    scanf("%d %d",&a,&b);
    scanf("%d %d",&c,&d);
    scanf("%d",&e);
    f=d-b;
    if(f>=(c-a)/e)
        printf("YES\n");
    else printf("NO\n");
    return 0;
}
