#include "bits/stdc++.h"

#define REP(i, n) for(decltype(n) i = 0; i < (n); i++)
#define REP2(i, x, n) for(decltype(x) i = (x); i < (n); i++)
#define RREP(i, n) for (decltype(n) i = (n) - 1;i >= 0; i--)

#define ALL(a) (a).begin(),(a).end()
#define SORT(c) sort((c).begin(),(c).end())
#define DESCSORT(c) sort(c.begin(), c.end(), greater<int>())

#define LL long long int
#define LD long double

#define INF 999999999
#define PI 3.14159265358979

#define _CRT_SECURE_NO_WARNINGS

using namespace std;

//================================================

int main() {
	ios::sync_with_stdio(false);
	cin.tie(0);

	vector<pair<int, int>>xy;
	
	int tmpA, tmpB, tmpC, tmpD;
	cin >> tmpA >> tmpB >> tmpC >> tmpD;

	xy.push_back(make_pair(tmpA, tmpB));
	xy.push_back(make_pair(tmpC, tmpD));

	int maxA = max(xy[0].first, xy[0].second);

	if (xy[0].first == xy[0].second && xy[1].first == xy[1].second && xy[0].first > xy[1].first) {
		cout << maxA + 1 << "\n";
	} else {
		cout << maxA << "\n";
	}
	return 0;
}