Compilare: user.cpp: In function ‘void BFS(int)’: user.cpp:25:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0; i<v[k].size(); ++i) ^ user.cpp: In function ‘int main()’: user.cpp:105:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0; j<sol[i].size(); ++j) ^ user.cpp:57:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("johnie.in", "r", stdin); ^ user.cpp:58:40: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("johnie.out", "w", stdout); ^ user.cpp:59:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &n, &m); ^ user.cpp:62:31: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d", &x, &y); ^