Compilare: user.cpp: In function ‘int main()’: user.cpp:39:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=n;i++) factorial[i]=(1LL*factorial[i-1]*i)%mod; ^ user.cpp:40:22: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=2;i<=n+1;i++) lg[i]=lg[i/2]+1; ^ user.cpp:41:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=1;i<=n;i++) ^ user.cpp:32:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permheap.in","r",stdin); ^ user.cpp:33:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("permheap.out","w",stdout); ^ user.cpp:34:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^