/in/foo.cc: In function 'void Work(int)':
/in/foo.cc:39:51: warning: array subscript has type 'char' [-Wchar-subscripts]
             while(top&&sta[top]!='('&&lvl[sta[top]]>=lvl[str[i]]){
                                                   ^
/in/foo.cc:39:64: warning: array subscript has type 'char' [-Wchar-subscripts]
             while(top&&sta[top]!='('&&lvl[sta[top]]>=lvl[str[i]]){
                                                                ^
/in/foo.cc: In function 'LL calc(LL, LL, char)':
/in/foo.cc:66:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^