foo.cc: In function ‘int main()’:
foo.cc:97:13: warning: variable ‘c11’ set but not used [-Wunused-but-set-variable]
   97 |     Complex c11=c1;
      |             ^~~
foo.cc:98:13: warning: variable ‘c22’ set but not used [-Wunused-but-set-variable]
   98 |     Complex c22=c2;
      |             ^~~
foo.cc:99:13: warning: variable ‘c33’ set but not used [-Wunused-but-set-variable]
   99 |     Complex c33=c3;
      |             ^~~