#include <bits/stdc++.h>
using namespace std;
int main() {
  vector<int> p(3);
  for (int i = 0; i < 3; i++) {
    cin >> p[i];
  }
  sort(p.begin(), p.end());
  if (p[0] + p[2] == p[1] * 2)
    cout << "Yes" << endl;
  else
    cout << "No" << endl;
}
