foo.cc: In function ‘bool dfs(int, int, int, int)’:
foo.cc:11:22: warning: unused variable ‘left’ [-Wunused-variable]
   11 |                 bool left=dfs(w1,d1,w2,d2);
      |                      ^~~~
foo.cc:16:22: warning: unused variable ‘right’ [-Wunused-variable]
   16 |                 bool right=dfs(w1,d1,w2,d2);
      |                      ^~~~~
foo.cc:18:19: warning: the address of ‘std::ios_base& std::left(ios_base&)’ will never be NULL [-Waddress]
   18 |         if (left&&right) return true;
      |                   ^~~~~
In file included from /nix/gcc-15.2.0/include/c++/15.2.0/streambuf:45,
                 from /nix/gcc-15.2.0/include/c++/15.2.0/bits/streambuf_iterator.h:37,
                 from /nix/gcc-15.2.0/include/c++/15.2.0/iterator:68,
                 from stdc++.h:56:
/nix/gcc-15.2.0/include/c++/15.2.0/bits/ios_base.h:1077:3: note: ‘std::ios_base& std::left(ios_base&)’ declared here
 1077 |   left(ios_base& __base)
      |   ^~~~
foo.cc:18:19: warning: the address of ‘std::ios_base& std::right(ios_base&)’ will never be NULL [-Waddress]
   18 |         if (left&&right) return true;
      |                   ^~~~~
/nix/gcc-15.2.0/include/c++/15.2.0/bits/ios_base.h:1085:3: note: ‘std::ios_base& std::right(ios_base&)’ declared here
 1085 |   right(ios_base& __base)
      |   ^~~~~