/* #region Head */ #include using namespace std; using ll = long long; using ull = unsigned long long; using ld = long double; using pll = pair; template using vc = vector; template using vvc = vc>; using vll = vc; using vvll = vvc; using vld = vc; using vvld = vvc; using vs = vc; using vvs = vvc; template using um = unordered_map; template using pq = priority_queue; template using pqa = priority_queue, greater>; template using us = unordered_set; #define REP(i, m, n) for (ll i = (m), i##_len = (ll)(n); i < i##_len; ++(i)) #define REPM(i, m, n) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; ++(i)) #define REPR(i, m, n) for (ll i = (m), i##_min = (ll)(n); i >= i##_min; --(i)) #define REPD(i, m, n, d) for (ll i = (m), i##_len = (ll)(n); i < i##_len; i += (d)) #define REPMD(i, m, n, d) for (ll i = (m), i##_max = (ll)(n); i <= i##_max; i += (d)) #define REPI(itr, ds) for (auto itr = ds.begin(); itr != ds.end(); itr++) #define ALL(x) begin(x), end(x) #define SIZE(x) ((ll)(x).size()) #define PERM(c) \ sort(ALL(c)); \ for (bool c##p = 1; c##p; c##p = next_permutation(ALL(c))) #define UNIQ(v) v.erase(unique(ALL(v)), v.end()); #define endl '\n' #define sqrt sqrtl #define floor floorl #define log2 log2l constexpr ll INF = 1'010'000'000'000'000'017LL; constexpr ll MOD = 1'000'000'007LL; // 1e9 + 7 constexpr ld EPS = 1e-12; constexpr ld PI = 3.14159265358979323846; template istream &operator>>(istream &is, vc &vec) { // vector 入力 for (T &x : vec) is >> x; return is; } template ostream &operator<<(ostream &os, vc &vec) { // vector 出力 (for dump) os << "{"; REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "" : ", "); os << "}"; return os; } template ostream &operator>>(ostream &os, vc &vec) { // vector 出力 (inline) REP(i, 0, SIZE(vec)) os << vec[i] << (i == i_len - 1 ? "\n" : " "); return os; } template istream &operator>>(istream &is, pair &pair_var) { // pair 入力 is >> pair_var.first >> pair_var.second; return is; } template ostream &operator<<(ostream &os, pair &pair_var) { // pair 出力 os << "(" << pair_var.first << ", " << pair_var.second << ")"; return os; } // map, um, set, us 出力 template ostream &out_iter(ostream &os, T &map_var) { os << "{"; REPI(itr, map_var) { os << *itr; auto itrcp = itr; if (++itrcp != map_var.end()) os << ", "; } return os << "}"; } template ostream &operator<<(ostream &os, map &map_var) { return out_iter(os, map_var); } template ostream &operator<<(ostream &os, um &map_var) { return out_iter(os, map_var); } template ostream &operator<<(ostream &os, set &set_var) { return out_iter(os, set_var); } template ostream &operator<<(ostream &os, us &set_var) { return out_iter(os, set_var); } template ostream &operator<<(ostream &os, pq &pq_var) { pq pq_cp(pq_var); os << "{"; if (!pq_cp.empty()) { os << pq_cp.top(), pq_cp.pop(); while (!pq_cp.empty()) os << ", " << pq_cp.top(), pq_cp.pop(); } return os << "}"; } // dump #define DUMPOUT cerr void dump_func() { DUMPOUT << endl; } template void dump_func(Head &&head, Tail &&... tail) { DUMPOUT << head; if (sizeof...(Tail) > 0) DUMPOUT << ", "; dump_func(move(tail)...); } // chmax (更新「される」かもしれない値が前) template > bool chmax(T &xmax, const U &x, Comp comp = {}) { if (comp(xmax, x)) { xmax = x; return true; } return false; } // chmin (更新「される」かもしれない値が前) template > bool chmin(T &xmin, const U &x, Comp comp = {}) { if (comp(x, xmin)) { xmin = x; return true; } return false; } // ローカル用 #define DEBUG_ #ifdef DEBUG_ #define DEB #define dump(...) \ DUMPOUT << " " << string(#__VA_ARGS__) << ": " \ << "[" << to_string(__LINE__) << ":" << __FUNCTION__ << "]" << endl \ << " ", \ dump_func(__VA_ARGS__) #else #define DEB if (false) #define dump(...) #endif struct AtCoderInitialize { static constexpr int IOS_PREC = 15; static constexpr bool AUTOFLUSH = false; AtCoderInitialize() { ios_base::sync_with_stdio(false), cin.tie(nullptr), cout.tie(nullptr); cout << fixed << setprecision(IOS_PREC); if (AUTOFLUSH) cout << unitbuf; } } ATCODER_INITIALIZE; string yes = "Yes", no = "No"; // string yes = "YES", no = "NO"; void yn(bool p) { cout << (p ? yes : no) << endl; } /* #endregion */ pll tsp(ll n, function dist) { vvll dp(1 << n, vll(n, INF)); // [state, last] -> min of max // REP(i, 0, n) dp[1 << i][i] = 0; dp[1][0] = 0; REP(state, 1, 1 << n) REP(from, 0, n) { if (~state & (1 << from)) continue; // 未訪問 if (dp[state][from] == INF) continue; // from が最後になるような巡回で state に至ることが不能 REP(to, 0, n) { if (state & (1 << to)) continue; // 訪問済み chmin(dp[state | (1 << to)][to], dist(dp[state][from], from, to)); } } // cout << *min_element(ALL(dp[(1 << n) - 1])) << endl; ll last = -1, len = INF; REP(i, 0, n) if (chmin(len, dp[(1 << n) - 1][i])) last = i; return make_pair(last, len); } // Problem void solve() { ll n, m, k; cin >> n >> m >> k; vll u(m), v(m); REP(i, 0, m) { cin >> u[i] >> v[i]; u[i]--, v[i]--; } vvll dist(n, vll(n, INF)); REP(i, 0, m) dist[u[i]][v[i]] = dist[v[i]][u[i]] = 1; REP(k, 0, n) REP(i, 0, n) REP(j, 0, n) { if (dist[i][k] != INF && dist[k][j] != INF) // i→k→j の経路が存在 chmin(dist[i][j], dist[i][k] + dist[k][j]); } vll travel_target_nodes; travel_target_nodes.push_back(0); ll coins = 0; REPR(target, n - 1, 1) { vvll dp(1 << k, vll(k, INF)); // dp[state][last] := state に至り,最後が last のときの最小距離 travel_target_nodes.push_back(target); // 仮に入れておく auto distl = [&](ll prev, ll from, ll to) { return min(INF, prev + dist[travel_target_nodes[from]][travel_target_nodes[to]]); }; auto [last, len] = tsp(SIZE(travel_target_nodes), distl); if (last == -1 || len > k) travel_target_nodes.pop_back(); else { coins += (1 << target) - 1; // dump(last, len, target); if (SIZE(travel_target_nodes) > k) break; } } cout << coins << endl; } // entry point int main() { solve(); return 0; }