Compilare: user.cpp: In function ‘void Read()’: user.cpp:17:34: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < S.length(); ++i) ^ user.cpp: In function ‘bool eval()’: user.cpp:40:29: warning: array subscript has type ‘char’ [-Wchar-subscripts] r = alphabet[ S[it] ]; ^ user.cpp: In function ‘void Solve()’: user.cpp:67:26: warning: array subscript has type ‘char’ [-Wchar-subscripts] alphabet[ seq[i] ] ^= 1; ^