Compilare: main.c: In function 'main': main.c:31:12: warning: array subscript has type 'char' [-Wchar-subscripts] ++b[a[0]]; ^ main.c:37:22: warning: array subscript has type 'char' [-Wchar-subscripts] if (b[a[j]] == 0) { ^ main.c:38:24: warning: array subscript has type 'char' [-Wchar-subscripts] ++b[a[j]]; ^ main.c:41:24: warning: array subscript has type 'char' [-Wchar-subscripts] ++b[a[j]]; ^ main.c:50:20: warning: array subscript has type 'char' [-Wchar-subscripts] --b[a[i]]; ^ main.c:51:22: warning: array subscript has type 'char' [-Wchar-subscripts] if (b[a[i]] == 0) { ^