Compilare: main.c: In function 'main': main.c:8:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("lacat.in","r",stdin),freopen("lacat.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:8:35: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("lacat.in","r",stdin),freopen("lacat.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:8:67: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("lacat.in","r",stdin),freopen("lacat.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~