#ifdef __LOCAL #define _GLIBCXX_DEBUG #endif #include #include using namespace std; using namespace atcoder; typedef unsigned long long ull; typedef long long ll; const double PI = 3.14159265358979323846; #define rep(i, n) for (ll i = 0; i < (ll)(n); i++) // a^p // 2^3 = 2 * 2^2 // 2^2 = 2 * (2^1) // 2^1 = 2 ll modpow(ll a, ll p, ll mod) { if (p == 0) return 1; if (p % 2 == 0) { ll half = modpow(a, p / 2, mod) % mod; return half * half % mod; } else { return a * modpow(a, p - 1, mod) % mod; } } // a^p ll powpow(ll a, ll p) { if (p == 0) return 1; if (p % 2 == 0) { ll half = pow(a, p / 2); return half * half; } else { return a * pow(a, p - 1); } } // a/b // https://qiita.com/drken/items/3b4fdf0a78e7a138cd9a ll moddiv(ll a, ll b, ll mod) { return a * modpow(b, mod - 2, mod); } // nCa を求める ll modCombination(ll n, ll a, ll mod) { if (n < 0 || a < 0 || n < a) return 0; if (n - a < a) { return modCombination(n, n - a, mod); } ll denominator = 1; // 分母 ll numerator = 1; // 分子 for (ll i = 0; i < a; i++) { denominator *= a - i; numerator *= n - i; denominator %= mod; numerator %= mod; } return numerator * modpow(denominator, mod - 2, mod) % mod; } vector> combination(ll n) { vector> C(n + 1, vector(n + 1)); C[0][0] = 1; rep(i, n) rep(j, i + 1) { C[i + 1][j + 1] += C[i][j]; C[i + 1][j] += C[i][j]; } return C; } // ref. https://drken1215.hatenablog.com/entry/2018/06/08/210000 class ModCombinationTale { private: ll n; ll mod; vector fac, finv, inv; public: ModCombinationTale(ll n, ll mod) : n(n), mod(mod) { fac.resize(n + 1); finv.resize(n + 1); inv.resize(n + 1); fac[0] = fac[1] = 1; finv[0] = finv[1] = 1; inv[1] = 1; for (ll i = 2; i <= n; i++) { fac[i] = fac[i - 1] * i % mod; inv[i] = mod - inv[mod % i] * (mod / i) % mod; finv[i] = finv[i - 1] * inv[i] % mod; } } ll operator()(ll n, ll k) { if (n < k) return 0; if (n < 0 || k < 0) return 0; return fac[n] * (finv[k] * finv[n - k] % mod) % mod; } }; class UnionFind { private: vector parents; public: UnionFind(ll n) : parents(n, -1) {} bool issame(ll x, ll y) { return root(x) == root(y); } bool merge(ll x, ll y) { if (issame(x, y)) return false; ll rx = root(x); ll ry = root(y); if (parents[rx] > parents[ry]) swap(rx, ry); // サイズ情報を更新 parents[rx] += parents[ry]; // yの親を更新 parents[ry] = rx; return true; } ll size(ll x) { return -parents[root(x)]; } ll root(ll x) { if (parents[x] < 0) return x; // 根の親の値に木の(-)サイズの情報を入れる return parents[x] = root(parents[x]); } }; // cf. https://qiita.com/drken/items/a14e9af0ca2d857dad23 vector enum_divisors(ll n) { vector res; // sqrt(n)まで試し割り for (ll i = 1; i * i <= n; i++) { if (n % i == 0) { res.push_back(i); // 重複しないならばiの相方であるn/iも約数 // e.g. n=25のときのi=5は重複 if (n / i != i) res.push_back(n / i); } } sort(res.begin(), res.end()); return res; } // cf. https://qiita.com/drken/items/a14e9af0ca2d857dad23 map prime_factors(ll n) { map res; // sqrt(n)まで試し割り for (ll a = 2; a * a <= n; a++) { if (n % a != 0) continue; // nで割れる限り割る while (n % a == 0) { res[a]++; n /= a; } } if (n != 1) res[n]++; return res; } ll gcd(ll a, ll b) { if (b == 0) return a; else return gcd(b, a % b); } ll lcm(ll a, ll b) { return (a / gcd(a, b)) * b; } // cf. https://qiita.com/drken/items/56a6b68edef8fc605821 class AccumSum2D { private: vector> sum; ll H; ll W; public: AccumSum2D(vector> &A) { H = (ll)A.size(); W = (ll)A[0].size(); sum.resize(H + 1, vector(W + 1)); for (ll i = 0; i < H; i++) { for (ll j = 0; j < W; j++) { sum[i + 1][j + 1] = sum[i][j + 1] + sum[i + 1][j] - sum[i][j] + A[i][j]; } } } // クエリ [x1, x2) × [y1, y2) の長方形区域の和 ll Sum(ll x1, ll x2, ll y1, ll y2) { return sum[x2][y2] - sum[x1][y2] - sum[x2][y1] + sum[x1][y1]; } }; // p/q struct fraction { ll p, q; fraction(ll _p = 0, ll _q = 1) : p(_p), q(_q) { if (q == 0) { p = 1; return; } if (q < 0) { p = -p; q = -q; } ll g = gcd(p, q); p /= g; q /= g; } bool operator<(const fraction &other) const { return p * other.q < q * other.p; } bool operator<=(const fraction &other) const { return p * other.q <= q * other.p; } bool operator==(const fraction &other) const { return p == other.p && q == other.q; } }; // res[i][c] := i 文字目以降で最初に文字 c が登場する index (存在しないときは n) vector> calcNext(const string &S) { ll n = (ll)S.size(); vector> res(n + 1, vector(26, n)); for (ll i = n - 1; i >= 0; --i) { for (ll j = 0; j < 26; ++j) res[i][j] = res[i + 1][j]; res[i][S[i] - 'a'] = i; } return res; } // ref. https://algo-logic.info/bridge-lowlink/ struct LowLink { vector> G; vector ord, low; vector visited; vector> bridges; LowLink(const vector> &G) : G(G) { visited.resize(G.size(), false); ord.resize(G.size(), 0); low.resize(G.size(), 0); ll k = 0; rep(i, (ll)G.size()) { if (visited[i]) continue; k = dfs(i, k); } } ll dfs(ll node, ll k, ll parent = -1) { visited[node] = true; ord[node] = k; low[node] = k; k++; for (auto g : G[node]) { if (!visited[g]) { k = dfs(g, k, node); low[node] = min(low[node], low[g]); if (ord[node] < low[g]) { bridges.emplace_back(node, g); } } else if (g != parent) { low[node] = min(low[node], ord[g]); } } return k; } }; int main() { cin.tie(nullptr); ios_base::sync_with_stdio(false); cout << fixed << setprecision(15); string N, M; cin >> N >> M; if (M == "0") { cout << 1 << endl; return 0; } ll s = ll(N.back() - '0'); vector history; ll current = s; while (1) { history.push_back(current); current *= s; current %= 10; if (s == current) break; } if ((ll)history.size() == 1) { cout << history[0] << endl; return 0; } // for (auto h : history) { // cout << h << endl; // } ll cycle = history.size(); ll mul = 1; ll m = 0; for (ll i = (ll)M.size() - 1; i >= 0; i--) { m += (ll(M[i] - '0') * mul) % cycle; mul *= 10; mul %= cycle; } m -= 1; if (m < 0) m += cycle; m %= cycle; cout << history[m] << endl; return 0; }