foo.cc: In function 'int main()':
foo.cc:20:21: warning: unused variable 'f' [-Wunused-variable]
  int x, n, j, i, y, f, s, s2;
                     ^
foo.cc:20:27: warning: unused variable 's2' [-Wunused-variable]
  int x, n, j, i, y, f, s, s2;
                           ^~
foo.cc:21:7: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
  scanf("%d%d", &x, &n);
  ~~~~~^~~~~~~~~~~~~~~~

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