Compilare: user.cpp: In function ‘void bfs(int)’: user.cpp:24:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < a[el].size() ; ++i) ^ user.cpp: In function ‘int main()’: user.cpp:70:41: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int j = 0 ; j < ans[i].size() ; j++) ^ user.cpp: In function ‘bool comparator(int, int)’: user.cpp:49:1: warning: control reaches end of non-void function [-Wreturn-type] } ^