Compilare: user.cpp: In function ‘void pregen()’: user.cpp:45:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int j = 0; j < v[i].size(); ++j ) ^ user.cpp:50:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( int j = 0; j < v[i].size(); ++j ) ^ user.cpp: In function ‘void push(char)’: user.cpp:104:69: warning: array subscript has type ‘char’ [-Wchar-subscripts] stiva[i][level] = A[i][ stiva[i][level - 1] + 1 ][ch]; ^