/in/foo.cc: In function 'void tarjan(int)':
/in/foo.cc:21:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<v[x].size();i++)
                 ~^~~~~~~~~~~~
/in/foo.cc: In function 'void find(int)':
/in/foo.cc:43:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<vi[x].size();i++)
                 ~^~~~~~~~~~~~~
/in/foo.cc: In function 'int main()':
/in/foo.cc:61:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int j=0;j<v[i].size();j++)
                     ~^~~~~~~~~~~~
/in/foo.cc:79:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
             for(int j=0;j<p[i].size();j++) ok[p[i][j]]=0;
                         ~^~~~~~~~~~~~
/in/foo.cc:90:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
         for(int i=0;i<v[x].size();i++)
                     ~^~~~~~~~~~~~