#include<iostream>
using namespace std;

int main()
{
	int number;
	cin >> number;
	for (int i = 10; i <= 99; i++)
	{

		int a = number % 10;
		int b = number / 10;
		int sym = a + b;
		if (sym < 0 && sym <= 18)
				cout << number;

		else cout << "Error";
		return 0;
		system("pause");


	}



}