#include <bits/stdc++.h>
using namespace std;

using ll = long long;
#define rep(i, n) for(int i = 0; i < n; i++)

int main() {
	int x, y, x2, y2;
	cin >> x >> y >> x2 >> y2;
	int ans = max(x, y);
	if(x && x == y && x2 && x2 == y2 && x > x2) ans++;
	cout << ans << endl;
}