func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<vector<char>> g;   map<long long, bool> dp;   void brute(int n, vector<int> &p) {     int x = find(p.begin(), p.end(), -1) - p.begin();     if (x == int(p.size())) {       vector<vector<char>> dp2(1 << n, vector<char>(n));       vector<int> pos1(n), pos2(n);       for (int i = 0; i < int(p.size()); i++) {         pos1[p[i]] = pos2[p[i]];         pos2[p[i]] = i;       }       for (int i = 0; i < int(n); i++)         if (g[pos1[i]][pos2[i]]) dp2[1 << i][i] = true;       for (int mask = 0; mask < int(1 << n); mask++)         for (int i = 0; i < int(n); i++)           if (dp2[mask][i]) {             for (int j = 0; j < int(n); j++)               if (!((mask >> j) & 1)) {                 dp2[mask | (1 << j)][j] |=                     (g[pos1[i]][pos1[j]] && g[pos2[i]][pos2[j]]);                 dp2[mask | (1 << j)][j] |=                     (g[pos1[i]][pos2[j]] && g[pos2[i]][pos1[j]]);               }           }       for (int i = 0; i < int(n); i++)         if (dp2[(1 << n) - 1][i]) {           long long num = 0;           for (int x : p) num = num * 6 + x;           dp[num] = true;           break;         }       return;     }     for (int y = x + 1; y < int(p.size()); ++y)       if (p[y] == -1) {         p[x] = p[y] = n;         brute(n + 1, p);         p[x] = p[y] = -1;       }   }   bool dfs(vector<int> p) {     vector<int> used(int(p.size()), -1);     int cnt = 0;     for (int i = 0; i < int(p.size()); i++)       if (used[p[i]] == -1) used[p[i]] = cnt++;     long long num = 0;     for (int &x : p) {       x = used[x];       num = num * 6 + x;     }     if (dp.count(num)) return dp[num];     bool res = false;     vector<int> cur(cnt);     for (int i = 0; i < int(p.size()); i++) ++cur[p[i]];     for (int i = 0; i < int(p.size()); i++)       if (cur[p[i]] > 2) {         int x = p[i];         for (int j = i + 1; j < int(p.size()); ++j)           if (p[j] == p[i]) {             p[i] = p[j] = cnt;             if (dfs(p)) {               res = true;               break;             }             p[i] = p[j] = x;           }         break;       }     return dp[num] = res;   }   void brute2(int n, vector<int> &p) {     int x = find(p.begin(), p.end(), -1) - p.begin();     if (x == int(p.size())) {       dfs(p);       return;     }     for (int i = 0; i < int(n + 1); i++) {       for (int y = x + 1; y < int(p.size()); ++y)         if (p[y] == -1) {           p[x] = p[y] = i;           brute2(max(n, i + 1), p);           p[x] = p[y] = -1;         }     }   }   int main() {     int n, m, k;     scanf( %d%d%d , &n, &m, &k);     g.resize(n, vector<char>(n));     for (int _ = 0; _ < int(m); _++) {       int v, u;       scanf( %d%d , &v, &u);       --v, --u;       g[v][u] = g[u][v] = 1;     }     vector<int> cur(n, -1);     brute(0, cur);     brute2(0, cur);     vector<long long> fact(k + 1);     fact[0] = 1;     for (int i = 1; i <= k; ++i) fact[i] = fact[i - 1] * i;     long long ans = 0;     for (auto it : dp)       if (it.second) {         long long num = it.first;         long long mx = 1;         while (num) {           mx = max(mx, num % 6 + 1);           num /= 6;         }         if (mx <= k) {           ans += fact[k] / fact[k - mx];         }       }     printf( %lld n , ans);     return 0;   }   