/in/foo.cc: In function 'int main()':
/in/foo.cc:19:18: error: 'pow' was not declared in this scope
   n = pow(a[i], n);
                  ^
/in/foo.cc:22:29: error: 'sqrt' was not declared in this scope
  for (int i = 0; i <= sqrt(n); i++) {
                             ^