Untitled

#include <iostream>
#include <string>
#include <iomanip>
#include <cmath>
using namespace std;

int main()
//9321
{
	int a = 0;
	cin >> a;
	if (a / 1000 - (a % 10) == (a / 100) % 10 + (a / 10) % 10) {
		cout << "YES";
	}
	else
		cout << "NO";
	
}