package main

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

func permutation(n int, k int) int {
	v := 1
	if 0 < k && k <= n {
		for i := 0; i < k; i++ {
			v *= (n - i)
		}
	} else if k > n {
		v = 0
	}
	return v
}

func factorial(n int) int {
	return permutation(n, n-1)
}

func nextInt() int {
	sc.Scan()
	i, e := strconv.Atoi(sc.Text())
	if e != nil {
		panic(e)
	}
	return i
}

var sc = bufio.NewScanner(os.Stdin)

func main() {
	var N int
	fmt.Scan(&N)

	sc.Split(bufio.ScanWords)
	A := make([]int, N)
	for i := 0; i < N; i++ {
		A[i] = nextInt()
	}

	sort.Sort(sort.IntSlice(A))

	var ans float64
	if A[0] == 0 {
		fmt.Println("-1")
	} else if A[len(A)-1] >= 4 {
		fmt.Println(int(math.Pow10(9) + 7))
	} else {
		ans = 1
		for i := 0; i < N; i++ {
			ans *= math.Pow(float64(A[i]), float64(factorial(A[i])))
		}
		fmt.Println(int(math.Pow10(9)+7) % int(ans))
	}
}