Same faces for different objects

PROBLEM:
Hello all. I am new to blender and need help. I have 2 objects (e.g 2 box mesh) I would like to export their properties as obj file in blender using python scripting. I would like to export the vertex of both objects firstly, followed by their faces. This is the code I am using below

CODE

import bpy

obj = list(bpy.data.objects)

    print("Cube\n")
    for a in obj:
        mesh =a.data
        for v in mesh.vertices:
        #random output compared to what we have in the original file
            print("v %.4f %.4f %.4f\n" % v.co[:]) #x,y,z coordinates     
    
    print("\n # 8 vertices\n")
    for a in obj:
        mesh =a.data
    
        print( "g " +a.name+ "\n")
        for p in mesh.polygons:             
            print("f")
            for i in p.vertices: 
                print(" %d" % (i + 1))  
            print( "\n")

OUTPUT

g.cube 1

f 1 2 4 3
f 3 4 8 7
f 7 8 6 5
f 5 6 2 1
f 3 7 5 1
f 8 4 2 6

g Cube.002

f 1 2 4 3
f 3 4 8 7
f 7 8 6 5
f 5 6 2 1
f 3 7 5 1
f 8 4 2 6


Observation:
Both faces of both objects are the same. This is not what I want. I would like the faces of the second object to start from 9 and so on. Please, how do I go about this?

That’s not possible definition of obj-files says:
1st object:

  • vertex of 1st object
  • faces of 1st object
    2nd object:
  • vertex of 2nd object
  • faces of 2nd object

so second object faces indexing starts from 0

Edit: or you must join both cubes in on object (having both the same material then)