Compilare: user.cpp: In function ‘char df(char)’: user.cpp:16:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] if (nf[x] == 0) ^ user.cpp:18:25: warning: array subscript has type ‘char’ [-Wchar-subscripts] for (i = 0; i < nf[x]; i++) ^ user.cpp:19:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] l = max(l, df(fii[x][i])); ^ user.cpp: In function ‘int main()’: user.cpp:43:23: warning: array subscript has type ‘char’ [-Wchar-subscripts] fii[x][nf[x]++] = y; ^