#include<bits/stdc++.h>
using namespace std;
int main() {
  vector<int> v(4);
  int sum = 0;
  for (int i = 0; i < 4; i++) cin >> v[i], sum += v[i];
  for (int i = 0; i < 16; i++) {
    int t = 0;
    for (int j = 0; j < 4; j++) {
      t += ((i >> j) & 1) * v[j];
    }
    if (t == sum - t) {
      cout << "Yes" << endl;
      return 0;
    }
  }
  cout << "No" << endl;
}
#include <bits/stdc++.h>

#define endl "\n"

using namespace std;


void setup() {
    #ifdef LOCAL
    freopen("input", "r", stdin);
    #else
    ios::sync_with_stdio(0);
    cin.tie(0);
    cout.tie(0);
    #endif
}


int main() {
    setup();
    int A, B, C, D;
    cin >> A >> B >> C >> D;

    int res = 0;
    if (A == C && B == D);
    else if (abs(A - C) + abs(B - D) <= 3) res = 1;
    else if (A + B == C + D || A - B == C - D) res = 1;
    else if (abs(A - C) + abs(B - D) <= 6) res = 2;
    else if (abs(A - B - C + D) <= 3 || abs(A + B - C - D) <= 3) res = 2;
    else if ((A + B) % 2 == (C + D) % 2) res = 2;
    else res = 3;
    cout << res << endl;
}