/in/foo.cc: In function 'void DFS(int, int)':
/in/foo.cc:8:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for(int k=0;k<g[i].size();k++){
              ~^~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:30:13: warning: suggest parentheses around '+' inside '>>' [-Wparentheses]
    int mid=A+B>>1;
            ~^~