Compilare: user.cpp: In function ‘int main()’: user.cpp:23:13: warning: array subscript has type ‘char’ [-Wchar-subscripts] muchie[a][b] = muchie[b][a] = true; ^ user.cpp:23:16: warning: array subscript has type ‘char’ [-Wchar-subscripts] muchie[a][b] = muchie[b][a] = true; ^ user.cpp:23:28: warning: array subscript has type ‘char’ [-Wchar-subscripts] muchie[a][b] = muchie[b][a] = true; ^ user.cpp:23:31: warning: array subscript has type ‘char’ [-Wchar-subscripts] muchie[a][b] = muchie[b][a] = true; ^ user.cpp:19:30: warning: ignoring return value of ‘int fscanf(FILE*, const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] fscanf(fin, "%d%d", &n, &m); ^