#include <iostream>
#include <vector>
int main()
{
	std::vector<char>str;
	bool flag = false;
	if (str.empty())
	{
		str.resize(1);
	}
	while (true)
	{
		std::cin >> str[0];
		if (str[0] == '0')
		{
			break;
		}
		else
		{
			str.push_back(str[0]);
		}
	}
	str.erase(str.begin());
	for (int i = 0,n = (unsigned)str.size(); i < n; i++)
	{
		if (str[0] == str[i])
		{
			flag = true;
			break;
		}
		else{}
	}

	if (flag)
	{
		std::cout << "YES" << std::endl;
	}
	else
	{
		std::cout << "NO" << std::endl;
	}
}