Compilare: user.cpp: In function ‘int main()’: user.cpp:40:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < next_give && j < next_recv) { ^ user.cpp:40:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] while (i < next_give && j < next_recv) { ^ user.cpp:13:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zeul.in", "r", stdin); ^ user.cpp:14:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("zeul.out", "w", stdout); ^ user.cpp:17:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &n, &m); ^ user.cpp:21:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d\n", &u, &v); ^