Compilare: user.cpp: In function ‘void solve()’: user.cpp:43:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = 0; k < V[i].size(); ++ k) ^ user.cpp: In function ‘void read()’: user.cpp:18:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("amenzi.in", "r", stdin); ^ user.cpp:19:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d %d", &n, &m, &k, &p); ^ user.cpp:22:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &a, &b, &c); ^ user.cpp:28:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &a, &b, &c); ^ user.cpp: In function ‘void write()’: user.cpp:54:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("amenzi.out", "w", stdout); ^ user.cpp:57:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &x, &y); ^