#include <bits/stdc++.h>

using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);i++)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

template<typename A, typename B> inline bool chmax(A &a, B b) { if (a<b) { a=b; return 1; } return 0; }
template<typename A, typename B> inline bool chmin(A &a, B b) { if (a>b) { a=b; return 1; } return 0; }

typedef unsigned long long ull;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, pii> P;

const ll INF = 1ll<<29;
const ll MOD = 1000000007;
const double EPS  = 1e-10;

string decr(string a) {
	if (a == "0") return "";
	
	reverse(ALL(a));
	REP(i, a.size()) {
		if (a[i] != '0') {
			a[i]--;
			break;
		}
		a[i] = '9';
	}
	
	if (a.size() > 1 && *(a.end() - 1) == '0') a.erase(a.end() - 1);
	
	reverse(ALL(a));
	
	return a;
}

int main() {
	string n, m;
	cin >> n >> m;
	
	int ans = -1;
	
	if (m == "0") ans = 1;
	else {
		int nlast = n[n.size() - 1] - '0';
		
		m = decr(m);
		
		vector<int> loop;
		loop.push_back(nlast);
		
		while (loop[0] != loop.back() * nlast % 10) loop.push_back(loop.back() * nlast % 10);
		
		int cal = 0;
		REP(i, m.size()) {
			cal = cal * 10 + m[i] - '0';
			cal %= loop.size();
		}
		ans = loop[cal];
		
	}
	
	cout << ans << endl;
	
	return 0;
}