package main

import (
	"bufio"
	"fmt"
	"os"
	"sort"
	"strconv"
	"strings"
)

func configure(scanner *bufio.Scanner) {
	// scanner.Split(bufio.ScanWords)
	scanner.Buffer(make([]byte, 1000005), 1000005)
}
func getNextString(scanner *bufio.Scanner) string {
	scanned := scanner.Scan()
	if !scanned {
		panic("scan failed")
	}
	return scanner.Text()
}
func getNextInt(scanner *bufio.Scanner) int {
	i, _ := strconv.Atoi(getNextString(scanner))
	return i
}
func getNextInt64(scanner *bufio.Scanner) int64 {
	i, _ := strconv.ParseInt(getNextString(scanner), 10, 64)
	return i
}
func getNextFloat64(scanner *bufio.Scanner) float64 {
	i, _ := strconv.ParseFloat(getNextString(scanner), 64)
	return i
}
func main() {
	fp := os.Stdin
	wfp := os.Stdout
	extra := 0
	if os.Getenv("I") == "IronMan" {
		fp, _ = os.Open(os.Getenv("END_GAME"))
		extra = 100
	}
	scanner := bufio.NewScanner(fp)
	configure(scanner)
	writer := bufio.NewWriter(wfp)
	defer func() {
		r := recover()
		if r != nil {
			fmt.Fprintln(writer, r)
		}
		writer.Flush()
	}()
	solve(scanner, writer)
	for i := 0; i < extra; i++ {
		fmt.Fprintln(writer, "-----------------------------------")
		solve(scanner, writer)
	}
}
func solve(scanner *bufio.Scanner, writer *bufio.Writer) {
	n := getNextInt(scanner)
	s := strings.Split(getNextString(scanner), " ")
	if len(s) == 3 {
		fmt.Fprintln(writer, "\"assert\"")
		return
	}
	aa := make([]int64, n)
	a, _ := strconv.ParseInt(s[0], 10, 64)
	aa[0] = a
	for i := 1; i < 3; i++ {
		aa[i] = getNextInt64(scanner)
	}
	m := map[int64]int{}
	for i := 0; i < 3; i++ {
		for j := 0; j < i; j++ {
			m[aa[i]+aa[j]] = 1
		}
	}
	ss := make([]int64, 0)
	for v := range m {
		ss = append(ss, v)
	}
	sort.SliceStable(ss, func(i, j int) bool {
		return ss[i] > ss[j]
	})
	fmt.Fprintln(writer, ss[1])
}