Compilare: user.c:48:5: warning: return type of ‘main’ is not ‘int’ [-Wmain] int main() ^ user.c: In function ‘main’: user.c:51:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm.in","r",stdin); ^ user.c:52:12: warning: ignoring return value of ‘freopen’, declared with attribute warn_unused_result [-Wunused-result] freopen("perm.out","w",stdout); ^ user.c:53:10: warning: ignoring return value of ‘scanf’, declared with attribute warn_unused_result [-Wunused-result] scanf("%hd%hd",&n,&m); ^