/in/foo.cc: In function 'int main()':
/in/foo.cc:29:34: warning: 'b_num' may be used uninitialized in this function [-Wmaybe-uninitialized]
     printf("%d %d\n",a_num,b_num);
                                  ^
/in/foo.cc:29:34: warning: 'a_num' may be used uninitialized in this function [-Wmaybe-uninitialized]