Compilare: main.cpp: In function 'int main()': main.cpp:25:8: warning: array subscript has type 'char' [-Wchar-subscripts] q[c].push_back(k); ^ main.cpp:28:16: warning: array subscript has type 'char' [-Wchar-subscripts] while (!q[c].empty()) { ^ main.cpp:29:14: warning: array subscript has type 'char' [-Wchar-subscripts] k = q[c].back(); ^ main.cpp:34:10: warning: array subscript has type 'char' [-Wchar-subscripts] q[c].pop_back(); ^