#include <iostream>
#include <vector>
#include <algorithm>
#include <map>
#include <string>
#include <queue>
#include <stack>
#include <math.h>
#include <set>
#include <cstdio>
#define ALL(obj) (obj).begin(),(obj).end()
#define RALL(obj) (obj).rbegin(),(obj).rend()
#define P pair<int, int>

#define MOD 1000000007
#define INF 1012345678
#define NINF (-2147483647-1)
#define LLINF 9223372036854775807
using ll = long long;
using namespace std;

int main() {
    int x, y, x2, y2;
    cin >> x >> y >> x2 >> y2;
    if (x == y && x2 == y2) {
        cout << x + 1 << endl;
    }
    else {
        cout << max(x, y) << endl;
    }
    getchar(); getchar();
    return 0;
}