Compilare: main.cpp: In function 'void solve()': main.cpp:37:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 1; i < str.size(); i++){ ~~^~~~~~~~~~~~ main.cpp:43:28: warning: array subscript has type 'char' [-Wchar-subscripts] if (type[str[i]] == type[str[s.top()]]){ ^ main.cpp:43:50: warning: array subscript has type 'char' [-Wchar-subscripts] if (type[str[i]] == type[str[s.top()]]){ ^