#include <iostream>
#include <vector>
#include <cstdio>
#include <sstream>
#include <map>
#include <string>
#include <algorithm>
#include <queue>
#include <cmath>
#include <set>
using namespace std;

int main(){
	int x,y;
	cin >> x >> y;
	int c,r;
	cin >> c >> r;

	int ans = max(x,y);

	if((x == c && x == 0 && r < y) || (y == r && y == 0 && c < x)) ans += 1;
	else if( x==y && c==r && c < x ) ans += 1;

	cout << ans << endl;

	return 0;
}