/in/foo.cc: In function 'int main()':
/in/foo.cc:17:19: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for(int i = 0;i <strlen(str);++i)if(str[i] == '('){
                 ~~^~~~~~~~~~~~
/in/foo.cc:32:24: warning: array subscript has type 'char' [-Wchar-subscripts]
     book[b[xun[xnum+1]]] = 0;
                        ^
/in/foo.cc:59:17: warning: array subscript has type 'char' [-Wchar-subscripts]
     if(book[s[i]]!=0)flag = 0;
                 ^