Compilare: user.cpp: In function ‘int bfs(int)’: user.cpp:30:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0; i<a[k].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:46:12: warning: unused variable ‘j’ [-Wunused-variable] int i, j, x, y; ^