Compilare: main.c: In function 'main': main.c:6:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("fact.in","r",stdin); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:7:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("fact.out","w",stdout); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:9:5: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^~~~~~~~~~~~~~