package main

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

func main() {
	r := bufio.NewReader(os.Stdin)
	w := bufio.NewWriter(os.Stdout)
    defer w.Flush()
	var N int
	fmt.Fscan(r, &N)
	var k int = 1
	for i := 0; i < N; i++ {
		var x int
		fmt.Fscan(r, &x)
		if k * x == 0 {
			k = 0
		} else if k * x % 9 == 0 {
			k = 9
		} else {
			k = k * x % 9
		}
	}
	if k == 0 {
		fmt.Fprintln(w, 0)
	} else if k % 9 == 0 {
		fmt.Fprintln(w, 9)
	} else {
		fmt.Fprintln(w, k % 9)
	}
}