#include <bits/stdc++.h>
// #include <atcoder/all>
using namespace std;
// using namespace atcoder;
typedef long long ll;
#define rep(i, n) for(ll i = 0, i##_len = (n); i < i##_len; i++)
#define reps(i, s, n) for(ll i = (s), i##_len = (n); i < i##_len; i++)
#define rrep(i, n) for(ll i = (n) - 1; i >= 0; i--)
#define rreps(i, e, n) for(ll i = (n) - 1; i >= (e); i--)
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) ((ll)(x).size())
#define len(x) ((ll)(x).length())
#define endl "\n"
template<class T> void chmax(T &a, const T b){ a = max(a, b); }
template<class T> void chmin(T &a, const T b){ a = min(a, b); }

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    // ifstream in("input.txt");
    // cin.rdbuf(in.rdbuf());
    ll a, b, c, d;
    cin >> a >> b >> c >> d;
    if (
        (a == (b + c + d)) ||
        (b == (a + c + d)) ||
        (c == (a + b + d)) ||
        (d == (a + b + c)) ||
        ((a + b) == (c + d)) ||
        ((a + c) == (b + d)) ||
        ((a + d) == (b + c))
    ) {
        cout << "Yes" << endl;
    }
    else {
        cout << "No" << endl;
    }
    return 0;
}

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <algorithm>
#include <vector>

int main(void){
  
  int a, b, c, d;
  int x, y;
  
  scanf("%d %d %d %d", &a, &b, &c, &d);
  printf("%d", b - c);
  
  return 0;
}