/in/foo.cc: In function 'void dfs(int, int, int, std::vector<int>)':
/in/foo.cc:26:7: warning: unused variable 'w' [-Wunused-variable]
   int w = e[i].w;
       ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:47:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int t = 0; t < es.size(); t++) {
                    ~~^~~~~~~~~~~