program cogs102;
const
maxn=100000;
g=10;
e=0.00001;
var
i,j,n:longint;
total:longint;
h,s1,v,l,k:extended;
h1,h2,t1,t2,t3,t4:extended;
begin
assign(input,'freefaller.in'); reset(input);
assign(output,'freefaller.out'); rewrite(output);
total:=0;
readln(h,s1,v,l,k,n);
if h-k-e>=0 then
t1:=sqrt((h-k-e)*0.2) else
t1:=0;
t2:=sqrt(h*0.2);
for i:=0 to n-1 do
begin
t3:=(s1-e-i)/v;
t4:=(s1-i+e+l)/v;
if (t1<=t4)and(t2>=t3) then
inc(total);
end;
writeln(total);
close(input);close(output);
end.