/in/foo.cc: In function 'int main()':
/in/foo.cc:81:14: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(i=0;i<path.size();i++)
             ~^~~~~~~~~~~~
/in/foo.cc:78:18: warning: 'y' may be used uninitialized in this function [-Wmaybe-uninitialized]
     dfs(pa,x,y,0);
                  ^
/in/foo.cc:78:18: warning: 'x' may be used uninitialized in this function [-Wmaybe-uninitialized]