package main

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

var sc = bufio.NewScanner(os.Stdin)

func Scanner() string {
	sc.Scan()
	return sc.Text()
}
func main() {
	buf := make([]byte, 0)
	sc.Buffer(buf, 100000007)
	sc.Split(bufio.ScanWords)
	a := make([]int, 5)
	for i := 4; i >= 0; i-- {
		a[i], _ = strconv.Atoi(Scanner())
	}
	ans := 0
	for i, j := 1, 1; i <= a[0]; i, j = j, i+j {
		if a[0] == i {
			count := 0
			num := i
			num2 := j
			for k := 0; k < 5; k++ {
				if a[k] == num {
					count++
					num, num2 = num2, num+num2
				} else {
					break
				}
			}
			ans = max(ans, count)
		}
	}
	fmt.Println(ans)
}

func max(x int, y int) int {
	if x >= y {
		return x
	} else {
		return y
	}
}