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 Rust (1.15.1) (judge verdict: Accepted)

#[allow(unused_macros)]
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        let mut next = || { iter.next().unwrap() };
        input_inner!{next, $($r)*}
    };
    ($($r:tt)*) => {
        let stdin = std::io::stdin();
        let mut bytes = std::io::Read::bytes(std::io::BufReader::new(stdin.lock()));
        let mut next = move || -> String{
            bytes
                .by_ref()
                .map(|r|r.unwrap() as char)
                .skip_while(|c|c.is_whitespace())
                .take_while(|c|!c.is_whitespace())
                .collect()
        };
        input_inner!{next, $($r)*}
    };
}
 
#[allow(unused_macros)]
macro_rules! input_inner {
    ($next:expr) => {};
    ($next:expr, ) => {};
 
    ($next:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($next, $t);
        input_inner!{$next $($r)*}
    };
}
 
#[allow(unused_macros)]
macro_rules! read_value {
    ($next:expr, ( $($t:tt),* )) => {
        ( $(read_value!($next, $t)),* )
    };
 
    ($next:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($next, $t)).collect::<Vec<_>>()
    };
 
    ($next:expr, chars) => {
        read_value!($next, String).chars().collect::<Vec<char>>()
    };
 
    ($next:expr, bytes) => {
        read_value!($next, String).into_bytes()
    };
 
    ($next:expr, usize1) => {
        read_value!($next, usize) - 1
    };
 
    ($next:expr, $t:ty) => {
        $next().parse::<$t>().expect("Parse error")
    };
}
 
use std::cmp::Ordering;
 
/// Equivalent to std::lowerbound and std::upperbound in c++
pub trait BinarySearch<T> {
    fn lower_bound(&self, &T) -> usize;
    fn upper_bound(&self, &T) -> usize;
}
 
impl<T: Ord> BinarySearch<T> for [T] {
    fn lower_bound(&self, x: &T) -> usize {
        let mut low = 0;
        let mut high = self.len();
 
        while low != high {
            let mid = (low + high) / 2;
            match self[mid].cmp(x) {
                Ordering::Less => {
                    low = mid + 1;
                }
                Ordering::Equal | Ordering::Greater => {
                    high = mid;
                }
            }
        }
        low
    }
 
    fn upper_bound(&self, x: &T) -> usize {
        let mut low = 0;
        let mut high = self.len();
 
        while low != high {
            let mid = (low + high) / 2;
            match self[mid].cmp(x) {
                Ordering::Less | Ordering::Equal => {
                    low = mid + 1;
                }
                Ordering::Greater => {
                    high = mid;
                }
            }
        }
        low
    }
}
 
 
 
 
 
 
use std::cmp;
use std::cmp::min;
use std::collections::BTreeMap;
use std::process;
use std::cmp::Ord;
use std::collections::HashMap;
use std::collections::HashSet;
use std::collections::VecDeque;
use std::collections::BTreeSet;
use std::mem;
 
#[derive(PartialEq, Eq)]
pub struct point(i64, i64, i64);
impl Ord for point {
    fn cmp(&self, other: &point) -> Ordering {
        self.0.cmp(&other.0)
    }
}
 
impl PartialOrd for point {
    fn partial_cmp(&self, other: &point) -> Option<Ordering> {
        Some(self.cmp(other))
    }
}
/*
impl PartialEq for point {
    fn eq(&self, other: &point) -> bool {
        self.0 == other.0
    }
}
impl Eq for point {
    fn eq(&self, other: &point) -> bool {
        self.0 == other.0
    }s
}*/
type P = (i64 , i64);
fn bfs(start:&P, goal:&P, map:&Vec<Vec<char>>) -> i64 {
        let dx = vec![1, 0, -1, 0];
        let dy = vec![0, 1, 0, -1];
        let s = (start.0, start.1);
        let g = (goal.0 , goal.1);
        let mut queue:VecDeque<P> = VecDeque::new();
        let mut d:Vec<Vec<i64>> = Vec::new();
        for i in 0..map.len(){
            d.push(Vec::new());
            for j in 0..map[i].len(){
                d[i].push(30000000);
            }
        }
        queue.push_back((s.0, s.1));
        d[s.0 as usize][s.1 as usize] = 0;
        while(queue.len()!=0){
            let mut p:P = queue[0];
            queue.pop_front();
            if p.0 == g.0 && p.1 == g.1{break;}
            for i in 0..4{
                let nx = p.0 + dx[i];
                let ny = p.1 + dy[i];
                if (0<=nx && nx <map.len() as i64 && 0<=ny &&ny<map[0].len() as i64 && map[nx as usize][ny as usize]!='#' && d[nx as usize][ny as usize] == 30000000 ){
                    queue.push_back((nx, ny));
                    d[nx as usize][ny as usize] = d[p.0 as usize][p.1 as usize] + 1;
                }
            }
 
        }
        d[goal.0 as usize][goal.1 as usize]
}
 
fn bfs01(start:&P, goal:&P, map:&Vec<Vec<char>>) -> i64 {
        let dx = vec![1, 0, -1, 0];
        let dy = vec![0, 1, 0, -1];
        let s = (start.0, start.1);
        let g = (goal.0 , goal.1);
        let mut queue:VecDeque<P> = VecDeque::new();
        let mut d:Vec<Vec<i64>> = Vec::new();
        for i in 0..map.len(){
            d.push(Vec::new());
            for j in 0..map[i].len(){
                d[i].push(30000000);
            }
        }
        queue.push_back((s.0, s.1));
        d[s.0 as usize][s.1 as usize] = 0;
        while(queue.len()!=0){
            let mut p:P = queue[0];
            queue.pop_front();
            if p.0 == g.0 && p.1 == g.1{break;}
            for i in 0..4{
                let nx = p.0 + dx[i];
                let ny = p.1 + dy[i];
                if (0<=nx && nx <map.len() as i64 && 0<=ny &&ny<map[0].len() as i64 && d[nx as usize][ny as usize] == 30000000 ){
                    if map[nx as usize][ny as usize] == '#'{
                        queue.push_back((nx, ny));
                        d[nx as usize][ny as usize] = d[p.0 as usize][p.1 as usize] + 1;
                    }
                    else{
                        queue.push_front((nx, ny));
                        d[nx as usize][ny as usize] = d[p.0 as usize][p.1 as usize];
                    }
                }
            }
 
        }
        d[goal.0 as usize][goal.1 as usize]
}
 
struct UnionFind{
    par:Vec<usize>,
    rank:Vec<usize>,
    size:Vec<usize>,    
}
impl UnionFind{
    fn init(n:usize) -> UnionFind{
        let mut par = vec![0;n];
        for i in 0..n{
            par[i] = i;    
        }
        UnionFind{
            par:par,
            rank:vec![0;n], 
            size:vec![1;n], 
        }
    }
    fn find(&mut self, x:usize) ->usize{
        if(self.par[x] == x){
            x    
        }
        else{
            let p = self.par[x];
            let res = self.find(p);
            self.par[x] = res;
            res
        }
    }
    fn same(&mut self, a:usize, b:usize)->bool{
        self.find(a) == self.find(b)    
    }
    fn unite(&mut self, a:usize, b:usize){
        let x = self.find(a);
        let y = self.find(b);
        if x != y{
            if (self.rank[x] < self.rank[y]){
                self.par[x] = y;
                self.size[y] += self.size[x];
            }
            else{
                self.par[y] = x;
                self.size[x] += self.size[y];
                if(self.rank[x] == self.rank[y]){ self.rank[x]+=1;}
            }
        }
    }
    fn check_size(&mut self, a:usize) -> usize{
        let x = self.find(a);
        let s = self.size[x];
        s    
    }
}
fn gcd(a:usize, b:usize)->usize{
    if b==0{return a;}
    gcd(b, a%b)
}
fn extgcd(a:usize, b:usize, x:&mut usize, y:&mut usize)->usize{
    let mut d = a;
    if b != 0{
        d = extgcd(b, a%b, y, x);
        *y -= (a/b) * (*x);    
    }    
    else{
        *x = 1;
        *y = 0;
    }
    d
}
 
fn main() {
    input!{
        n:usize,
        pp:[usize;n],
    };
    let mut res = 1;
    for i in 1..n{
        if i == 1{
            res = gcd(pp[i], pp[i-1]);    
        }    
        else{
            res = gcd(res, pp[i]);
        }
    }
    println!("{}", res);
}