func_code_string: #include <bits/stdc++.h>   using namespace std;   vector<vector<int> > V(7);   vector<vector<string> > S(7);   set<string> SS;   int n, m;   void DFS(int node, string T) {     if (T.length() == n) {       SS.insert(T);       return;     }     for (int i = 0; i < S[node].size(); i++) {       string R = S[node][i];       string E;       E += R[1];       if (T.length() + 2 == n) {         DFS(0, T + R);       } else         DFS(R[0] -  a , T + E);     }   }   int main() {     cin >> n >> m;     string y;     char C;     char A[m];     for (int i = 0; i < m; i++) {       cin >> y >> C;       A[i] = C;       S[C -  a ].push_back(y);     }     for (int i = 0; i < m; i++) {       if (A[i] ==  a ) {         DFS(A[i] -  a ,   );       }     }     cout << SS.size() << endl;     return 0;   }   