Compilare: user.c: In function ‘main’: user.c:30:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.in","r",stdin),freopen("domino.out","w",stdout),scanf("%d\n",&n); ^ user.c:30:43: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.in","r",stdin),freopen("domino.out","w",stdout),scanf("%d\n",&n); ^ user.c:30:74: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] freopen("domino.in","r",stdin),freopen("domino.out","w",stdout),scanf("%d\n",&n); ^ user.c:32:14: warning: ignoring return value of ‘fgets’, declared with attribute warn_unused_result [-Wunused-result] fgets(r,5,stdin),a[i]=r[0]-'0',b[i]=r[2]-'0',f[10*a[i]+b[i]]++; ^