package main

import (
	"fmt"
	"bufio"
	"os"
	"strconv"
	"math"
)

func check3 (a int) bool{
	if	a%3==0 {
		return true
	}
	for ;a > 0; a/= 10{
		if a%10==3{
			return true
		}
	}
	return false;
}

func main() {
	var x, y = nextInt(), nextInt()
	var x2, y2 = nextInt(), nextInt()
	if(x<0){
		x *= -1
		x2 *= -1
	}
	if(y<0){
		y *= -1
		y2 *= -1
	}
	if x==y && x2==y2 && x2<x {
		fmt.Println(int(math.Max(float64(x), float64(y))) + 1)
	} else {
		fmt.Println(int(math.Max(float64(x), float64(y))))
	}
}


var s = bufio.NewScanner(os.Stdin)

func next() string {
	s.Split(bufio.ScanWords)
	s.Scan()
	return s.Text()
}
func nextLine() string {
	s.Split(bufio.ScanLines)
	s.Scan()
	return s.Text()
}

func nextInt() int {
	i, e := strconv.Atoi(next())
	if e != nil {
		panic(e)
	}
	return i
}
func nextLong() int64 {
	i, e := strconv.ParseInt(next(), 10, 64)
	if e != nil {
		panic(e)
	}
	return i
}