Compilare: main.c: In function 'main': main.c:21:5: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("fibo.in","r",stdin),freopen("fibo.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:21:34: warning: ignoring return value of 'freopen', declared with attribute warn_unused_result [-Wunused-result] freopen("fibo.in","r",stdin),freopen("fibo.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~ main.c:21:65: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result] freopen("fibo.in","r",stdin),freopen("fibo.out","w",stdout),scanf("%d",&n); ^~~~~~~~~~~~~~