bus.cpp: In function 'int main()':
bus.cpp:22:9: warning: unused variable 'j' [-Wunused-variable]
  int i, j;
         ^
bus.cpp:24:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &N, &M);
  ~~~~~^~~~~~~~~~~~~~~~
bus.cpp:25:27: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for(i=1; i<=M; i++) scanf("%d%d%d%d", &E[i].A, &E[i].B, &E[i].X, &E[i].Y);
                      ~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
bus.cpp:45:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d", &Q);
  ~~~~~^~~~~~~~~~
bus.cpp:49:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   scanf("%d", &x);
   ~~~~~^~~~~~~~~~