Compilare: main.c: In function 'erase_val': main.c:50:18: warning: unused variable 'next' [-Wunused-variable] hash_line *next = it->next->next; ^~~~ main.c: In function 'main': main.c:61:3: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("hashuri.in", "r", stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:62:3: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("hashuri.out", "w", stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:64:8: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] for (scanf("%d", &N); N; --N) { ^~~~~~~~~~~~~~~ main.c:65:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &type, &key); ^~~~~~~~~~~~~~~~~~~~~~~~~~~