When an interrupt occurs, an Operating System

An operating system contains 3 user processes each requiring 2 units of resource R.The minimum number of units of R such that no deadlocks will ever arise is

Heap allocation is required for languages.

Given the following Pascal like program segment:

Procedure A;

     x,y:intger;

     Procedure B;

            x,z:real;

            S1

     end B;

     Procedure C;

            i:integer;

            S2;

     end C;

end A;

The variables accessible in S1 and S2 are