#include 

//
//  The assert macro provides an easy to use debugging tool.  You place assert
//  statements at points where you expect some condition to be true.  It seems
//  that conditions want to defy your expectations a lot.  Getting a message
//  from the computer at the earliest point helps.
//
//  If you are pretty sure that n should be a positive number <= 100 use this
//
    assert ( n > 0 && n <= 100 );

//
//  Define NDEBUG either in the code with #define NDEBUG or when compiling to
//  disable the assert macros.  The effect is like the macro wasn't there.
//  There is no time wasted.
//
//  g++ -DNDEBUG program.cpp
//