Compilare: user.cpp: In function ‘int main()’: user.cpp:497:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("next.in", "r", stdin); ^ user.cpp:498:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("next.out", "w", stdout); ^ user.cpp:500:12: warning: ignoring return value of ‘char* gets(char*)’, declared with attribute warn_unused_result [-Wunused-result] gets(s); ^ user.cpp:502:22: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld", &d); ^ user.cpp:507:13: warning: ‘a’ may be used uninitialized in this function [-Wmaybe-uninitialized] n+=a; ^ /tmp/ccloVQrO.o: In function `main': user.cpp:(.text.startup+0x61): warning: the `gets' function is dangerous and should not be used.