Compilare: user.cpp: In function ‘void write(int, const std::vector<Edge, std::allocator<Edge> >&)’: user.cpp:143:34: warning: format ‘%lu’ expects argument of type ‘long unsigned int’, but argument 2 has type ‘std::vector<Edge, std::allocator<Edge> >::size_type {aka unsigned int}’ [-Wformat=] printf("%lu\n", answer.size()); ^ user.cpp: In function ‘void read_data(int&, int&, std::vector<Node>*)’: user.cpp:73:26: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &m); ^ user.cpp:76:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d %d", &x, &y, &cost); ^