/in/foo.cc: In function 'int main()':
/in/foo.cc:6:6: warning: unused variable 'cnt' [-Wunused-variable]
  int cnt=0,mx=0;
      ^~~
/in/foo.cc:19:17: warning: 'bb' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<aa<<" "<<bb<<endl;
                 ^~
/in/foo.cc:19:12: warning: 'aa' may be used uninitialized in this function [-Wmaybe-uninitialized]
  cout<<aa<<" "<<bb<<endl;
            ^~~