Compilare: user.c: In function ‘bkt’: user.c:325:6: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if (valid(st, k)) ^ user.c: In function ‘main’: user.c:341:6: warning: unused variable ‘S’ [-Wunused-variable] int S; ^ user.c:343:8: warning: ignoring return value of ‘fscanf’, declared with attribute warn_unused_result [-Wunused-result] fscanf(in, "%d", &N); ^