#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#define sz(x) ((int)x.size())
#define all(x) (x).begin(), (x).end()
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define mset(x,y) memset(x,y,sizeof(x))
#define rep(i,n) for(int i=0;i<int(n);i++)
#define per(i,n) for(int i=int(n)-1;i>=0;i--)
#define rng(i,a,b) for(int i=int(a);i<=int(b);i++)
#define gnr(i,b,a) for(int i=int(b);i>=int(a);i--)
using namespace std;
using namespace __gnu_pbds;
using ordered_set = tree<int, null_type, less<int>, rb_tree_tag, tree_order_statistics_node_update>;
#ifdef LOCAL
#define dmp(...) _dmp(#__VA_ARGS__, __VA_ARGS__)
#else
#define dmp(...) (__VA_ARGS__)
#endif
template<class T> using vt=vector<T>;
template<class T> using vvt=vt<vt<T>>;
template<class TA,class TB> void chmax(TA&a,TB b){if(a<b)a=b;}
template<class TA,class TB> void chmin(TA&a,TB b){if(b<a)a=b;}
template<class TA,class TB>
ostream& operator<<(ostream& os,const pair<TA,TB>& p){
	return os<<"{"<<p.fi<<","<<p.se<<"}";
}
template<class T> ostream& operator<<(ostream& os,const vt<T>& v){
	os<<"{";for(auto& e:v)os<<e<<",";return os<<"}";
}
template<class TH> void _dmp(const char *sdbg, TH h){cout<<sdbg<<"="<<h<<endl;}
template<class TH, class... TA> void _dmp(const char *sdbg, TH h, TA...a){
while(*sdbg!=',')cout<<*sdbg++;cout<<"="<<h<<","; _dmp(sdbg+1, a...);
}
template<class T> void make_unique(vt<T>& v) {
	sort(all(v));v.erase(unique(all(v)),v.end());
}
typedef long long ll;
typedef long double ld;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
typedef vector<int> vi;
int ri(){int x;cin>>x;return x;}
ll rll(){ll x;cin>>x;return x;}
vi rvi(int n){vi v;rep(i,n)v.pb(ri());return v;}
int n;
vi a;
void MAIN() {
	int i,j;
	cin>>n;
	for(i=0;i<n;i++) {
		int x;cin>>x;
		a.pb(x);
	}
	make_unique(a);
	int mn=1e9;
	for(i=1;i<sz(a);i++) {
		mn=min(mn,__gcd(a[0],a[i]));
	}
	if(sz(a)==1)cout<<a[0];
	else cout<<mn;
}
int main() {
	ios::sync_with_stdio(false);cin.tie(0);
	int T=1;
	//cin>>T;
	for(int tt=1;tt<=T;tt++) {
		MAIN();
	}
	return 0;
}
#include <bits/stdc++.h>

#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define FOR(i,n,m) for(int i=(int)(n); i<=(int)(m); i++)
#define RFOR(i,n,m) for(int i=(int)(n); i>=(int)(m); i--)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define RITR(x,c) for(__typeof(c.rbegin()) x=c.rbegin();x!=c.rend();x++)
#define setp(n) fixed << setprecision(n)

template<class T> bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; }
template<class T> bool chmin(T &a, const T &b) { if (a>b) { a=b; return 1; } return 0; }

#define ll long long
#define vll vector<ll>
#define vi vector<int>
#define pll pair<ll,ll>
#define pi pair<int,int>

#define all(a) (a.begin()),(a.end())
#define rall(a) (a.rbegin()),(a.rend())
#define fi first
#define se second
#define pb push_back
#define ins insert

#define debug(a) cerr<<(a)<<endl
#define dbrep(a,n) rep(_i,n) cerr<<(a[_i])<<" "; cerr<<endl
#define dbrep2(a,n,m) rep(_i,n){rep(_j,m) cerr<<(a[_i][_j])<<" "; cerr<<endl;}

using namespace std;

template<class A, class B>
ostream &operator<<(ostream &os, const pair<A,B> &p){return os<<"("<<p.fi<<","<<p.se<<")";}
template<class A, class B>
istream &operator>>(istream &is, pair<A,B> &p){return is>>p.fi>>p.se;}

/* Some Libraries */

//-------------------------------------------------

const ll INF = LONG_LONG_MAX;

int main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    ll B,C; cin>>B>>C;
    auto f = [&](ll x){
        bool f1 = B>0;
        bool f2 = x>0;
        if (f1^f2){
            return abs(x-B)*2+1;
        }else{
            if (x<B){
                return abs(x-B)*2;
            }else{
                return abs(x-B)*2+2;
            }
        }
    };

    pll a,b;
    {
        ll l=B-C/2,r=max(B,B+C/2-1);
        a = pll(l,r);
    }
    {
        C--;
        ll l=-B-C/2,r=-B+C/2;
        b = pll(l,r);
    }
    if (a>b) swap(a,b);
    if (a.se>=b.fi){
        ll ans = (b.se-a.fi+1);
        cout<<ans<<"\n";
    }else{
        ll ans = (a.se-a.fi+1) + (b.se-b.fi+1);
        cout<<ans<<"\n";
    }

    return 0;
}
