/in/foo.cc: In function 'int main()':
/in/foo.cc:17:32: warning: 'b' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<max<<" "<<xiao<<" "<<b<<" "<<a<<endl;
                                ^~~
/in/foo.cc:17:37: warning: 'a' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<max<<" "<<xiao<<" "<<b<<" "<<a<<endl;
                                     ^