Compilare: main.c: In function 'main': main.c:5:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("sumfact.in","r",stdin),freopen("sumfact.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:5:37: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("sumfact.in","r",stdin),freopen("sumfact.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:5:71: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("sumfact.in","r",stdin),freopen("sumfact.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~