Compilare: user.cpp: In function ‘void solve()’: user.cpp:79:43: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (p = 0; p < V[x].size(); ++ p) ^ user.cpp: In function ‘void read()’: user.cpp:42:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gather.in", "r", stdin); ^ user.cpp:43:34: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &k, &n, &m); ^ user.cpp:48:30: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] w[i] = x; ^ user.cpp:52:53: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &e.x, &e.y, &e.c, &e.d); ^ user.cpp: In function ‘void write()’: user.cpp:108:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("gather.out", "w", stdout); ^