Passing command line arguments in c++11 using environment variables

Platform- Ubuntu.

I have an executable - EXECUTE (source file name-EXECUTE.cpp.).

I am passing command line arg:-

e.g. -

EXECUTE 10

Now the problem is how can i use this 10 to overwrite a global variable in different file- EXECUTE_A.cpp.

NOTE-

I am not allowed to make any changes to EXECUTE.cpp.

So I cant do anything like this in EXECUTE.cpp -

EXECUTE_A::function(10)

I am new to c++, i hope that my problem statement is clear enough. Thanks in advance.