#include <bits/stdc++.h>

using namespace std;

const std::vector<int> dx = {1, -1, 0, 0, 1, 1, -1, -1}, dy = {0, 0, 1, -1, 1, -1, 1, -1};

int main() {
  ios::sync_with_stdio(false);
  cin.tie(nullptr);
  int gx, gy, ngx, ngy;
  cin >> gx >> gy >> ngx >> ngy;
  if (ngx < gx && ngy < gy && ngx == ngy && gx == gy) {
    cout << max(gx, gy) + 1 << '\n';
  } else {
    cout << max(gx, gy) << '\n';
  }
  return 0;
}