foo.cc: In function 'bool check(int)':
foo.cc:22:19: error: 'sqrt' was not declared in this scope
  for (i = 2; i <= sqrt(sum); i++)
                   ^~~~
foo.cc:22:19: note: suggested alternative: 'qsort'
  for (i = 2; i <= sqrt(sum); i++)
                   ^~~~
                   qsort
foo.cc: In function 'int main()':
foo.cc:54:2: error: 'memset' was not declared in this scope
  memset(temp, 0, n);
  ^~~~~~
foo.cc:54:2: note: suggested alternative: 'wmemset'
  memset(temp, 0, n);
  ^~~~~~
  wmemset

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