/in/foo.cc: In function 'int main()':
/in/foo.cc:6:21: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d",&W,&N);
                     ^
/in/foo.cc:7:44: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int i=1; i<=N; i++) scanf("%d",&w[i]);
                                            ^