foo.cc: In function 'int main()':
foo.cc:6:17: error: 'n' was not declared in this scope
    6 |  for (int i=0;i<n;i++)
      |                 ^
foo.cc:10:13: error: 'n' was not declared in this scope
   10 |  for (int i=n-1;i>=1;i--)
      |             ^

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