var
h,s1,v,l,k,t1,t2,x1,x2:real;
ans,i,n:longint;
begin
assign(input,'freefaller.in');
assign(output,'freefaller.out');
reset(input);rewrite(output);
read(h,s1,v,l,k,n);
ans:=0;
t1:=sqrt(h/5);
t2:=sqrt((h-k)/5);
x1:=v*t2;
x2:=v*t1;
x1:=s1-x1+l;
x2:=s1-x2;
for i:=0 to n-1 do
begin
if (i>=x2-0.00001) and (i<=x1+0.00001) then inc(ans);
end;
if h<=k then writeln(n) else writeln(ans);
close(input);close(output);
end.