program z630;
uses crt;
var z:real;
i,a,b:integer;
function sum(a,b:integer):integer;
begin
if b=0 then sum:=a
else if b>0 then sum:=sum(a+1,b-1)
else sum:=sum(a-1,b+1);
end;
BEGIN
writeln('vvesti a');
readln(a);
writeln('vvesti b');
readln(b);
z:=sum(a,b);
write (z);
readln;
END.