Compilare: user.cpp: In function ‘int main()’: user.cpp:56:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0; j < V[i].size(); ++ j) ^ user.cpp:36:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("reborn.in", "r", stdin); ^ user.cpp:37:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("reborn.out", "w", stdout); ^ user.cpp: In function ‘int Get()’: user.cpp:24:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(Buf, 1, MaxB, stdin), Ptr = 0; ^ user.cpp:29:48: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(Buf, 1, MaxB, stdin), Ptr = 0; ^