#include <bits/stdc++.h>
using namespace std;
const int maxn = 100 + 10;
int a[maxn], sum, aim;
bool jud() {
  for (int i = 0; i < 16; i++) {
    int now = 0;
    for (int j = 0; j < 4; j++) {
      if ((1 << j) & i) {
        now += a[j];
      }
    }
    if (now * 2 == sum) return true;
  }
  return false;
}
int main() {
  for (int i = 1; i <= 4; i++) {
    scanf("%d", a + i);
    sum += a[i];
  }
  sort(a + 1, a + 1 + 4);
  if (jud()) {
    printf("YES\n");
  } else {
    printf("NO\n");
  }
  getchar();
  getchar();
  return 0;
}
