foo.cc: In function 'int main()':
foo.cc:14:30: error: 'n' was not declared in this scope
   14 |     for (int i = 2; i <=sqrt(n); i++)
      |                              ^
foo.cc:18:7: error: 'flag' was not declared in this scope
   18 |       flag  = 2;
      |       ^~~~
foo.cc:22:14: error: 'flag' was not declared in this scope
   22 |     if (7 == flag)
      |              ^~~~
foo.cc:31:1: error: expected '}' at end of input
   31 | }
      | ^
foo.cc:5:1: note: to match this '{'
    5 | {
      | ^

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