Compilare: user.cpp: In function ‘int main()’: user.cpp:44:23: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=i*2; j<=n; j=j+i) ^ user.cpp:9:27: warning: unused variable ‘d’ [-Wunused-variable] unsigned long n, s=0, i, d, f, a[200000]; ^ user.cpp:9:30: warning: unused variable ‘f’ [-Wunused-variable] unsigned long n, s=0, i, d, f, a[200000]; ^