#include<iostream>
#include<cstdio>
#include<cstring>
#include <cstdlib>  
#include <cmath>   
#include<cctype>
#include<string>
#include<set>
#include <map>
#include<algorithm>
#include <functional>
#include<vector>
#include<climits>
#include<stack>
#include<queue>
#include <deque>
#include <climits>
#include <typeinfo>
#include <utility> 
#define all(x) (x).begin(),(x).end()
#define rep(i,m,n) for(int i = m;i < n;++i)
#define pb push_back
#define fore(i,a) for(auto &i:a)
#define rrep(i,m,n) for(int i = m;i >= n;--i)
#define INF INT_MAX/2
using namespace std;
using ll = long long;
using R = double;
const ll MOD = 1e9 + 7;
const ll inf = 1LL << 50;
struct edge { ll from; ll to; ll cost; };


int main(){
	int x, y, x2, y2;
	cin >> x >> y >> x2 >> y2;

	if (x == 0 || y == 0) {
		if (y == 0)swap(x, y), swap(x2, y2);

		if (x2 == 0 && 0 < y2 && y2 < y)cout << y + 2 << endl;
		else cout << y << endl;
	}
	else if(x != y){
		cout << max(x, y) << endl;
	}
	else {
		if (0 < y2 && y2 < y) {
			cout << x + 1 << endl;
		}
		else {
			cout << x << endl;
		}
	}

	return 0;
}