Compilare: main.c: In function 'main': main.c:29:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("fact.in","r",stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:30:2: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("fact.out","w",stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:33:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%i",&p); ^~~~~~~~~~~~~~