Compilare: user.c: In function ‘main’: user.c:17:9: warning: array subscript has type ‘char’ [-Wchar-subscripts] while (scanf("%c",&c) && c!='\n') t[c]++; ^ user.c:9:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("fences.in","rt",stdin); ^ user.c:10:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("fences.out","wt",stdout); ^ user.c:13:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d\n",&n); ^