#include <iostream>
#include <vector>
#include <deque>
#include <stack>
#include <memory>
#include <functional>
#include <algorithm>
#include <map>
#include <list>
#include <complex>
#include <string>
#include <cstdio>
#include <cstring>
#include <cstdlib>
#include <cmath>
#include <numeric>
#include <array>
using namespace std;
typedef std::pair<int, int> pii;
typedef long long int ll;

#define pb push_back

int dx[9] {-1, 0, 1, -1, 0, 1, -1, 0, 1};
int dy[9] {1, 1, 1, 0, 0, 0, -1, -1, -1};



int main(){
	
	int x, y;
	int mx ,my;

	cin >> x >> y;
	cin >> mx >> my;

	int max_xy = max(x,y);
	int min_xy = min(x,y);
	int max_mxy = max(mx,my);
	int min_mxy = min(mx,my);


	if(max_xy == min_xy) {
		if(max_mxy == min_mxy && max_xy > max_mxy){
			std::cout << max_xy + 1 << std::endl;
			return 0;
		}else{
			std::cout << max_xy << std::endl;
			return 0;
		}
	}else{
		std::cout << max_xy << std::endl;
	}

	return 0;
}