foo.cc: In function ‘int main()’:
foo.cc:104:13: warning: variable ‘c11’ set but not used [-Wunused-but-set-variable]
  104 |     Complex c11=c1;
      |             ^~~
foo.cc:105:13: warning: variable ‘c22’ set but not used [-Wunused-but-set-variable]
  105 |     Complex c22=c2;
      |             ^~~
foo.cc:106:13: warning: variable ‘c33’ set but not used [-Wunused-but-set-variable]
  106 |     Complex c33=c3;
      |             ^~~