Compilare: user.cpp: In function ‘int main()’: user.cpp:33:44: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < GF[a + 1].size(); i++) ^ user.cpp:42:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < GB[a].size(); i++) ^ user.cpp:15:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pcb.in", "r", stdin); ^ user.cpp:16:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("pcb.out", "w", stdout); ^ user.cpp:18:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d", &n, &m, &x); ^ user.cpp:22:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &a, &b); ^