Consider the following set of productions that define a subset of the C++ programming language:

::= int main() { return 0; }

::= |

::= | | |

|

::= { }

::= if ( )

| if ( ) | if ( ) else

| if ( ) else

| if ( ) else

| if ( ) else

::= while ( )

| while ( )

::= = ;

::= ;

|

::= | |

::= + | - | * | /

::= int

| double

::=

::=

::= [empty]

|

|

::= [empty]

|

::= [A-Z] | [a-z] | _

::= [0-9]