/in/foo.cc: In function 'int main(int, const char**)':
/in/foo.cc:25:68: warning: operation on 'j' may be undefined [-Wsequence-point]
     for (int j=forstart; (flag&&j<forend-1)||(!flag&&j>forend+1); j= (p3==1) ? ++j:--j){
                                                                   ~^~~~~~~~~~~~~~~~~~~
/in/foo.cc:45:2: error: expected ';' before 'cout'
  cout<<ans<<endl;
  ^~~~