var
h,s,v,l,k,t,t1,g:real;
n,i,total:longint;
begin
assign(input,'freefaller.in');reset(input);
assign(output,'freefaller.out');rewrite(output);
read(h,s,v,l,k,n);
g:=10;
t:=sqrt((h-k)*2/g);
t1:=sqrt(h*2/g);
total:=0;
for i:=n-1 downto 0 do
if ((s-v*t-i)/v<=t1-t+0.00001) and (s+l-v*t>=i) then inc(total);
write(total);
close(input);close(output);
end.