Compilare: user.cpp: In function ‘int main()’: user.cpp:7:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prim.in","r",stdin); ^ user.cpp:8:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("prim.out","w",stdout); ^ user.cpp:9:18: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld",&k); ^ user.cpp:31:21: warning: ‘e’ may be used uninitialized in this function [-Wmaybe-uninitialized] printf("%lld\n",e*e); ^