#include <iostream>
#include <vector>
#include <string>
#include <cstring>
#include <math.h>
#include <cmath>
#include <limits.h>
#include <map>
#include <set>
#include <queue>
#include <algorithm>
#include <functional>
#include <stdio.h>
using namespace std;

long long MOD = 1000000007;

int main() {
    
    long long x1,x2,y1,y2;
    cin >> x1 >> y1 >> x2 >> y2;
    
    if ( x1 == y1 && x2 == y2 && x1 > x2 ) {
        cout << x1 + 1 << endl;
    }
    else {
        cout << max( x1, y1 ) << endl;
    }
    
    return 0;
}