/in/foo.cc: In function 'void insert(char*)':
/in/foo.cc:20:21: warning: array subscript has type 'char' [-Wchar-subscripts]
         int k=c[s[i]];
                     ^
/in/foo.cc: In function 'void match(char*)':
/in/foo.cc:53:21: warning: array subscript has type 'char' [-Wchar-subscripts]
         int k=c[s[i]];
                     ^
/in/foo.cc: In function 'int query(char*)':
/in/foo.cc:67:21: warning: array subscript has type 'char' [-Wchar-subscripts]
         int k=c[s[i]];
                     ^