Compilare: user.cpp: In function ‘bool fac(int)’: user.cpp:27:18: warning: array subscript has type ‘char’ [-Wchar-subscripts] else r = u[rs[p]], ++p; ^ user.cpp: In function ‘int main()’: user.cpp:50:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < s .size(); i++) ^ user.cpp:59:6: warning: array subscript has type ‘char’ [-Wchar-subscripts] u[c] = !u[c]; ^ user.cpp:59:14: warning: array subscript has type ‘char’ [-Wchar-subscripts] u[c] = !u[c]; ^