Compilare: main.cpp: In function 'char calc(int, int)': main.cpp:22:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < adia[nod].size(); ++i) { ~~^~~~~~~~~~~~~~~~~~ main.cpp:31:16: warning: array subscript has type 'char' [-Wchar-subscripts] ++frq[i]; ^ main.cpp:36:21: warning: array subscript has type 'char' [-Wchar-subscripts] while (frq[i] == 0 && i < 18) ^ main.cpp:38:19: warning: array subscript has type 'char' [-Wchar-subscripts] if (!frq[i]) ^ main.cpp:42:16: warning: array subscript has type 'char' [-Wchar-subscripts] --frq[i]; ^