Compilare: user.cpp: In function ‘int main()’: user.cpp:12:49: warning: operation on ‘j’ may be undefined [-Wsequence-point] t=(t+2*(k-j)*(v[k++]-v[j--]))%1000000007; ^ user.cpp:12:49: warning: operation on ‘k’ may be undefined [-Wsequence-point] user.cpp:7:85: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("galagie.in","r",stdin),freopen("galagie.out","w",stdout),scanf("%d",&n); ^ user.cpp:7:85: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:7:85: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] user.cpp:9:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",v+i); ^