Compilare: user.cpp: In function ‘void solve()’: user.cpp:58:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i = 0; i < V[x.x].size(); ++ i) ^ user.cpp: In function ‘void read()’: user.cpp:29:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mine.in", "r", stdin); ^ user.cpp:30:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d", &n, &m); ^ user.cpp:34:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &x, &y, &k); ^ user.cpp:38:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &w); ^ user.cpp:41:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &q[i]); ^ user.cpp: In function ‘void write()’: user.cpp:77:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("mine.out", "w", stdout); ^