Untitled

#include <iostream>
using namespace std;

int main()
{
    int chuslo;

    cin >> chuslo;

    int firstCH = 0;
    int secondCH = 0;
    int therdCH = 0;
    int forthCH = 0;

    if (chuslo >= 1000 and chuslo <= 9999) {
        firstCH = chuslo / 1000;
        secondCH = (chuslo / 100) % 10;
        therdCH = (chuslo / 10) % 10;
        forthCH = chuslo % 10;
    }

;

    if (firstCH - forthCH == secondCH + therdCH) {
        cout << "YES";
    }
    else {
        cout << "NO";
    }


}