package main

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

func main() {
	sc := NewScanner(os.Stdin)
	x, _ := sc.NextLong()
	y, _ := sc.NextLong()
	x2, _ := sc.NextLong()
	y2, _ := sc.NextLong()

	fmt.Println(solve(x, y, x2, y2))
}

func solve(x, y, x2, y2 int64) int64 {
	res := x
	if res < y {
		res = y
	}
	if x == 0 || y == 0 {
		return res
	}
	if x == y && x2 == y2 {
		return res + 1
	} else {
		return res
	}
}

type scanner struct {
	*bufio.Scanner
}

func NewScanner(r io.Reader) *scanner {
	return &scanner{
		bufio.NewScanner(r),
	}
}

func (s *scanner) Next() (string, error) {
	s.Scanner.Split(bufio.ScanWords)
	return s.nextToken()
}

func (s *scanner) NextLine() (string, error) {
	s.Scanner.Split(bufio.ScanLines)
	return s.nextToken()
}

func (s *scanner) nextToken() (string, error) {
	sc := s.Scanner
	if sc.Scan() {
		return sc.Text(), nil
	}
	if sc.Err() != nil {
		return "", sc.Err()
	}
	return "", io.EOF
}

func (s *scanner) NextBytes() ([]byte, error) {
	s.Scanner.Split(bufio.ScanWords)
	return s.nextb()
}

func (s *scanner) NextLineBytes() ([]byte, error) {
	s.Scanner.Split(bufio.ScanLines)
	return s.nextb()
}

func (s *scanner) nextb() ([]byte, error) {
	sc := s.Scanner
	if sc.Scan() {
		return sc.Bytes(), nil
	}
	if sc.Err() != nil {
		return nil, sc.Err()
	}
	return nil, io.EOF
}

func (s *scanner) NextInt() (int, error) {
	token, err := s.Next()
	if err != nil {
		return 0, err
	}
	return strconv.Atoi(token)
}

func (s *scanner) NextLong() (int64, error) {
	token, err := s.Next()
	if err != nil {
		return 0, err
	}
	return strconv.ParseInt(token, 10, 64)
}