Compilare: user.cpp: In function ‘void solve()’: user.cpp:44:47: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (k = 0; k < V[j].size(); ++ k) ^ user.cpp: In function ‘void read()’: user.cpp:9:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("oras.in", "r", stdin); ^ user.cpp:10:20: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &n); ^ user.cpp: In function ‘void write()’: user.cpp:70:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("oras.out", "w", stdout); ^