foo.cc:10:1: error: expected initializer before 'bool'
 bool comp(int x, int y) {
 ^~~~
foo.cc: In function 'int main()':
foo.cc:26:3: error: 'r' was not declared in this scope
   r[i] = i;
   ^
foo.cc:29:7: error: 'r' was not declared in this scope
  sort(r, r + n, comp);
       ^
foo.cc:29:17: error: 'comp' was not declared in this scope
  sort(r, r + n, comp);
                 ^~~~

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