Problem:
Score : 300 points

Problem Statement

There are N monsters, numbered 1, 2, ..., N.

Initially, the health of Monster i is A_i.

Below, a monster with at least 1 health is called alive.

Until there is only one alive monster, the following is repeated:

A random alive monster attacks another random alive monster.

As a result, the health of the monster attacked is reduced by the amount equal to the current health of the monster attacking.

Find the minimum possible final health of the last monster alive.

Constraints

All values in input are integers.

2 \leq N \leq 10^5

1 \leq A_i \leq 10^9

Input

Input is given from Standard Input in the following format:

N
A_1 A_2 ... A_N

Output

Print the minimum possible final health of the last monster alive.

Sample Input 1

4
2 10 8 40

Sample Output 1

2

When only the first monster keeps on attacking, the final health of the last monster will be 2, which is minimum.

Sample Input 2

4
5 13 8 1000000000

Sample Output 2

1

Sample Input 3

3
1000000000 1000000000 1000000000

Sample Output 3

1000000000

Solution in Go (1.6) (judge verdict: Accepted)

package main

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

const (
	initialBufSize = 1024
	maxBufSize     = 1e6
)

var (
	scanner = bufio.NewScanner(os.Stdin)
	// writer  = bufio.NewWriterSize(os.Stdout, 1000000)
)

func main() {
	scanner.Split(bufio.ScanWords)
	// scanner.Buffer(make([]byte, initialBufSize), maxBufSize)
	// defer writer.Flush()
	n := scanInt()
	a := scanInts(n)
	sort.Ints(a)

	ans := a[0]
	for i := 1; i < n; i++ {
		ans = gcd(ans, a[i])
	}
	fmt.Println(ans)
}

func scanInt() int {
	i, _ := strconv.Atoi(scanString())
	return i
}

func scanInts(size int) []int {
	ints := make([]int, size)
	for i := 0; i < size; i++ {
		ints[i] = scanInt()
	}
	return ints
}

func scanFloat64() float64 {
	f, _ := strconv.ParseFloat(scanString(), 64)
	return f
}

func scanFloat64s(size int) []float64 {
	f := make([]float64, size)
	for i := 0; i < size; i++ {
		f[i] = scanFloat64()
	}
	return f
}

func scanString() string {
	scanner.Scan()
	return scanner.Text()
}

func scanStrings(size int) []string {
	s := make([]string, size)
	for i := 0; i < size; i++ {
		s[i] = scanString()
	}
	return s
}

func abs(n int) int {
	if n < 0 {
		return -n
	}
	return n
}

func pow(x, y int) int {
	return int(math.Pow(float64(x), float64(y)))
}

// greatest common divisor(最大公約数)
func gcd(a, b int) int {
	for {
		mod := a % b
		if mod == 0 {
			return b
		}
		a, b = b, mod
	}
}

// latest common multiple(最小公倍数)
func lcm(a, b int) int {
	return (a / gcd(a, b)) * b
}

func fact(n int) int {
	ret := 1
	for i := 1; i <= n; i++ {
		ret *= i
	}
	return ret
}

func perm(n, r int) int {
	ret := 1
	for i := 0; i < r; i++ {
		ret *= n
		n--
	}
	return ret
}

func isPrimeNum(n int) bool {

	if n <= 1 {
		return false
	}

	l := int(math.Sqrt(float64(n)) + 1.)
	for i := 2; i < l; i++ {
		if n%i == 0 {
			return false
		}
	}

	return true
}