/in/foo.cc: In function 'int main()':
/in/foo.cc:29:37: warning: 'num2' may be used uninitialized in this function [-Wmaybe-uninitialized]
     cout << a[num1] << " " << a[num2] << endl;
                                     ^
/in/foo.cc:29:24: warning: 'num1' may be used uninitialized in this function [-Wmaybe-uninitialized]
     cout << a[num1] << " " << a[num2] << endl;
                        ^~~