foo.cc: In function 'int main()':
foo.cc:7:14: error: 'n' was not declared in this scope
    7 |         cin>>n;
      |              ^
foo.cc:10:20: error: expected ';' before 'a'
   10 |                 cin a[i];
      |                    ^~
      |                    ;
foo.cc:10:17: warning: statement has no effect [-Wunused-value]
   10 |                 cin a[i];
      |                 ^~~

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