Compilare: user.cpp: In function ‘int main()’: user.cpp:18:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("compact2.in" , "r" , stdin); ^ user.cpp:19:43: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("compact2.out" , "w" , stdout); ^ user.cpp:20:21: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &n);//f >> n; ^ user.cpp:22:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d" , &v[i]);//f >> v[i]; ^