/in/foo.cc: In function 'int main()':
/in/foo.cc:95:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   if (G[i].size() > siz) flag[i] = 1;
       ~~~~~~~~~~~~^~~~~
/in/foo.cc:105:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (int j = 0;j < G2[i].size();++j) {
                  ~~^~~~~~~~~~~~~~
/in/foo.cc:115:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for (int i = 0;i < G[a].size();++i) {
                    ~~^~~~~~~~~~~~~
/in/foo.cc:123:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    for (int i = 0;i < G2[a].size();++i) {
                   ~~^~~~~~~~~~~~~~