#include <bits/stdc++.h>   using namespace std;   int main() {     int a[4];     for (int i = 0; i < 4; i++) cin >> a[i];     int sumtotal = a[0] + a[1] + a[2] + a[3];     if (sumtotal % 2 != 0) {       cout <<  NO ;       return 0;     }     for (int i = 0; i < 4; i++) {       if (a[i] == sumtotal - a[i]) {         cout <<  YES ;         return 0;       } else         for (int j = 0; j < 4; j++) {           if (i != j)             if ((a[i] + a[j]) == (sumtotal - a[i] - a[j])) {               cout <<  YES ;               return 0;             }         }     }     cout <<  NO ;   }   