/in/foo.cc: In function 'void R(int&)':
/in/foo.cc:12:10: warning: suggest parentheses around '+' inside '<<' [-Wparentheses]
   v = (v + (v << 2) << 1) + (ch^'0');
        ~~^~~~~~~~~~
/in/foo.cc: In constructor 'node::node(int, int, int, int)':
/in/foo.cc:19:14: warning: 'node::c' will be initialized after [-Wreorder]
  int to, pa, c, w;
              ^
/in/foo.cc:19:10: warning:   'int node::pa' [-Wreorder]
  int to, pa, c, w;
          ^~
/in/foo.cc:20:2: warning:   when initialized here [-Wreorder]
  node (int to, int c, int pa, int w): to(to), c(c), pa(pa), w(w) {}
  ^~~~
/in/foo.cc: In function 'std::pair<long long int, long long int> feiyongliu(int, int, int)':
/in/foo.cc:47:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i = 0 ; i < q[x].size(); ++i) {
                     ~~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:79:6: warning: unused variable 'x' [-Wunused-variable]
  int x, y, c, w;
      ^
/in/foo.cc:79:9: warning: unused variable 'y' [-Wunused-variable]
  int x, y, c, w;
         ^
/in/foo.cc:79:12: warning: unused variable 'c' [-Wunused-variable]
  int x, y, c, w;
            ^
/in/foo.cc:79:15: warning: unused variable 'w' [-Wunused-variable]
  int x, y, c, w;
               ^