var a,b,c:longint;
begin
readln(a);
if a mod 2=0 then
a:=a-1
else a:=a*2;
writeln(a);
end.
if x mod 2 = 0 then x:=x-1
else x:=2*x;
var a,b,c:longint;
begin
readln(a);
if a mod 2=0 then
a:=a-1
else a:=a*2;
writeln(a);
end.
if x mod 2 = 0 then x:=x-1
else x:=2*x;