The root directory of a disk should be placed:

Consider a system having m resources of the same type. These resources are shared by 3 processes A, B and C, which have peak demands of 3, 4 and 6 respectively. For what value of m deadlock will not occur?

What does the following code do?

var a, b : integer;
begin
    a:=a+b;
    b:=a-b;
    a:=a-b;
end;