#include <bits/stdc++.h>
int main() {
  int candies[4];
  int sum = 0;
  for (size_t i = 0; i < 4; i++) {
    scanf("%d", &candies[i]);
    sum = sum + candies[i];
  }
  for (size_t i = 0; i < 4; i++) {
    if (candies[i] == (sum - candies[i])) {
      printf("YES\n");
      return 0;
    }
    if (i > 0) {
      if ((candies[0] + candies[i]) == (sum - (candies[0] + candies[i]))) {
        printf("YES\n");
        return 0;
      }
    }
  }
  printf("NO\n");
  return 0;
}
