function swap(k:integer):integer;
var d,r:integer;
begin
r:=0;
while k>0 do begin
d:=k mod 10;
  k:=k div 10;
  r:=r*10+d;
end;
swap:=r;
end;

var k,i,r:integer;
begin
close(input); close(output);
assign(input,'INPUT.TXT'); assign(output,'OUTPUT.TXT');
reset(input); rewrite(output);
r:=0;
readln(k);
for i:=1 to k do if i+swap(i)=k then inc(r);
write(r);
close(input); close(output);
end.lor].