program P;
var a,b:integer;
function f(a,b:integer):integer;
begin
 if a>0 then f:=f(a-1,b-1)+2
 else if b<0 then f:=f(a,b+1) -1
 else f:=b;
end;
begin
 a:=5; b:=2;
 writeln(f(a,b))
end.