/in/foo.cc: In function 'int main()':
/in/foo.cc:8:18: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
     for(int i=0;i<st.size()-1;i++)
                 ~^~~~~~~~~~~~
/in/foo.cc:14:15: warning: array subscript has type 'char' [-Wchar-subscripts]
         if(a[j])
               ^
/in/foo.cc:19:15: warning: array subscript has type 'char' [-Wchar-subscripts]
         if(a[j])
               ^
/in/foo.cc:20:22: warning: array subscript has type 'char' [-Wchar-subscripts]
             cout<<a[j];
                      ^