#include <stdio.h>
signed main(void){
 
 int kyori,hayasa,a,v,b,w,t;
 
(void)scanf("%d,%d,%d,%d,%d",&a,&v,&b,&w,&t);
 
 
if(a>=b){
    kyori=a-b;
    
}else{
    kyori=b-a;
}
 
if(v>=w){
    hayasa=v-w;    
}else{
    hayasa=w-v;   
}
 
if(kyori>hayasa*t){    
    printf("NO\n");   
}else{
    printf("YES\n");   
}
 
 return(0);
    
}