foo.cc: In function ‘void bfs()’:
foo.cc:50:33: warning: comparison of integer expressions of different signedness: ‘int’ and ‘std::__cxx11::basic_string<char>::size_type’ {aka ‘long unsigned int’} [-Wsign-compare]
   50 | for(int j=t.s.find(a[i]);j>=0&&j<=(t.s.length()-a[i].length());j=t.s.find(a[i],j+1))
      |                                ~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~