Untitled

#include <iostream>
using namespace std;

int main()
{
	int a, b, c, d, f, g;
	cin >> a;
	b = a / 1000;
	c = a / 100 % 10;
	d = a / 10 % 10;
	f = a % 10;
	if (b - f==c + d) {
		cout << "YES";
	}
	else {
		cout << "No";
	}
}