foo.cc: In function 'int main()':
foo.cc:7:13: error: 'sqrt' was not declared in this scope
    7 |     int k = sqrt(n);
      |             ^~~~
foo.cc:18:6: error: expected '}' at end of input
   18 |     }
      |      ^
foo.cc:4:1: note: to match this '{'
    4 | {
      | ^
foo.cc:5:9: warning: unused variable 'i' [-Wunused-variable]
    5 |     int i, n;
      |         ^

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