func_code_string: #include <bits/stdc++.h>   using namespace std;   bool v[6];   int a[100009][6], maxx = -1, t;   long long m = 1e9 + 7;   struct pi {     long long ah[60][60];   };   pi multi(pi x, pi y) {     pi z;     for (int i = 1; i <= t; i++) {       for (int j = 1; j <= t; j++) {         z.ah[i][j] = 0;         for (int k = 1; k <= t; k++)           z.ah[i][j] = (z.ah[i][j] % m + x.ah[i][k] % m * y.ah[k][j] % m) % m;         z.ah[i][j] %= m;       }     }     return z;   }   pi quimul(pi x, long long int n) {     pi an;     for (int i = 1; i <= t; i++) an.ah[i][i] = 1;     for (; n; n >>= 1) {       if (n & 1) an = multi(an, x);       x = multi(x, x);     }     return an;   }   int main() {     long long n;     int x, v, p[600], zh[90][90];     char c =  a , u;     for (int i = 1; i <= 52; i++)       for (int j = 1; j <= 52; j++) zh[i][j] = 1;     for (int i = 1; i <= 26; i++) p[(int)c + i - 1] = i;     c =  A ;     for (int i = 27; i <= 52; i++) p[(int)c + i - 27] = i;     cin >> n >> t >> v;     for (int i = 0; i < v; i++) {       scanf(  %c %c , &c, &u);       zh[p[(int)c]][p[(int)u]] = 0;     }     pi ans;     for (int i = 1; i <= t; i++)       for (int j = 1; j <= t; j++) ans.ah[i][j] = zh[i][j];     ans = quimul(ans, n - 1);     long long int pp = 0;     for (int i = 1; i <= t; i++)       for (int j = 1; j <= t; j++) pp = (pp + ans.ah[i][j]) % m;     cout << (pp + m) % m << endl;   }   