/in/foo.cc: In function 'long long int count(long long int)':
/in/foo.cc:7:28: error: 'sqrt' was not declared in this scope
  for (int i = 1; i < sqrt(x); i++)
                            ^
/in/foo.cc:11:16: error: 'sqrt' was not declared in this scope
  int m = sqrt(x);
                ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:29:12: warning: unused variable 'ans' [-Wunused-variable]
  long long ans = 0;
            ^~~