/in/foo.cc: In function 'int main()':
/in/foo.cc:22:23: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &n, &m);
                       ^
/in/foo.cc:23:49: 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", &a[i]);
                                                 ^
/in/foo.cc:24:49: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  for (int j = 1; j <= n; j++) scanf("%d", &b[j]);
                                                 ^