var t:text;
var a,b,i,si,sp,x,s,sa,sb,xa,xb,sfa,sfb:longint;

begin
assign(t,'simpla.in'); reset(t);
read(t,a,b); close(t); assign(t,'simpla.out'); rewrite(t);
dec(a);
sfa:=0; sfb:=0;
xa:=a; xb:=b;
while (xa>0) do
  begin
    sa:=sa+xa mod 10;
    xa:=xa div 10;
  end;
while (xb>0) do
  begin
    sb:=sb+xb mod 10;
    xb:=xb div 10;
  end;
if sa mod 2=0 then inc(sfa);
if sb mod 2=0 then inc(sfb);
{x:=a mod 10;
for i:=0 to x do
  if (sa+i) mod 2 = 0 then inc(sfa);
x:=b mod 10;
for i:=0 to x do
  if (sb+i) mod 2 = 0 then inc(sfb);
}
if a mod 2=0 then sa:=a div 2
  else sa:=sfa+(a-1) div 2;
if b mod 2=0 then sb:=b div 2
  else sb:=sfb+(b-1) div 2;
write(t,sb-sa);
close(t);
end.