foo.cc: In function 'int main()':
foo.cc:21:12: warning: format '%d' expects argument of type 'int', but argument 2 has type 'long long int' [-Wformat=]
   21 |  printf ("%d", ans);
      |           ~^   ~~~
      |            |   |
      |            int long long int
      |           %lld
foo.cc:13:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   13 |  scanf ("%lld", &n);
      |  ~~~~~~^~~~~~~~~~~~
foo.cc:14:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   14 |  scanf ("%lld %lld", &a, &b);
      |  ~~~~~~^~~~~~~~~~~~~~~~~~~~~
foo.cc:17:8: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
   17 |  scanf ("%lld %lld", &f[i].l, &f[i].r), f[i].v = f[i].l - f[i].r;
      |  ~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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