foo.cc: In function 'int main()':
foo.cc:7:29: error: 'a' was not declared in this scope
    7 |  for(int i=1;i<=n;i++) cin>>a[i];
      |                             ^
foo.cc:8:7: error: 'a' was not declared in this scope
    8 |  sort(a+1,a+n+1);
      |       ^

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