func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MOD = 1000000007, dx[] = {0, 1, 0, -1}, dy[] = {1, 0, -1, 0};   const double eps = 1e-8;   void read(int &k) {     k = 0;     char x = getchar();     while (x <  0  || x >  9 ) x = getchar();     while (x >=  0  && x <=  9 ) {       k = k * 10 - 48 + x;       x = getchar();     }   }   long long mul[40][40], tmp[40][40], now[40], nxt[40];   int L, R, no[10][10];   long long powe(long long a, long long b) {     long long ret = 1;     for (; b; b >>= 1, a = a * a % MOD)       if (b & 1) ret = ret * a % MOD;     return ret;   }   long long solve1(int x) {     if (x == 0) return 0;     memset(mul, 0, sizeof mul);     for (int i = 0; i < 5; i++)       for (int j = 0; j < 5; j++)         if (!no[i][j])           for (int k = 1; k < 5; k++)             if (!no[j][k])               if ((i != 4 || j != 1 || k != 3) && (i != 3 || j != 1 || k != 4))                 mul[i * 6 + j][j * 6 + k] = 1;     for (int i = 0; i < 5; i++)       for (int j = 0; j < 5; j++) mul[i * 6 + j][35] = 1;     mul[35][35] = 1;     memset(now, 0, sizeof now);     now[0] = 1;     for (; x; x >>= 1) {       if (x & 1) {         memset(nxt, 0, sizeof nxt);         for (int k = 0; k < 36; k++)           if (now[k])             for (int j = 0; j < 36; j++)               nxt[j] = (nxt[j] + now[k] * mul[k][j]) % MOD;         memcpy(now, nxt, sizeof now);       }       memset(tmp, 0, sizeof tmp);       for (int i = 0; i < 36; i++)         for (int k = 0; k < 36; k++)           if (mul[i][k])             for (int j = 0; j < 36; j++)               tmp[i][j] = (tmp[i][j] + mul[i][k] * mul[k][j]) % MOD;       memcpy(mul, tmp, sizeof mul);     }     long long ret = 0;     for (int i = 0; i < 36; i++) ret = (ret + now[i]) % MOD;     return (ret + MOD - 1) % MOD;   }   long long solve2(int x) {     long long ret = 0;     x--;     int y = x;     for (int T = 1; T <= 4; T++) {       x = y;       memset(mul, 0, sizeof mul);       for (int i = 0; i < 5; i++)         for (int j = 0; j < 5; j++)           if (!no[i][j])             for (int k = 1; k < 5; k++)               if (!no[j][k])                 if ((i != 4 || j != 1 || k != 3) && (i != 3 || j != 1 || k != 4))                   mul[i * 6 + j][j * 6 + k] = 1;       for (int i = 0; i < 5; i++)         for (int j = 0; j < 5; j++) mul[i * 6 + j][35] = 1;       mul[35][35] = 1;       memset(now, 0, sizeof now);       now[T] = 1;       for (; x; x >>= 1) {         if (x & 1) {           memset(nxt, 0, sizeof nxt);           for (int k = 0; k < 36; k++)             if (now[k])               for (int j = 0; j < 36; j++)                 nxt[j] = (nxt[j] + now[k] * mul[k][j]) % MOD;           memcpy(now, nxt, sizeof now);         }         memset(tmp, 0, sizeof tmp);         for (int i = 0; i < 36; i++)           for (int k = 0; k < 36; k++)             if (mul[i][k])               for (int j = 0; j < 36; j++)                 tmp[i][j] = (tmp[i][j] + mul[i][k] * mul[k][j]) % MOD;         memcpy(mul, tmp, sizeof mul);       }       for (int i = 0; i < 36; i++) ret = (ret + now[i]) % MOD;     }     return (ret + MOD) % MOD;   }   long long calc(int x) {     if (x == 0) return 0;     return (solve1(x) + solve2((x + 1) / 2)) % MOD * powe(2, MOD - 2) % MOD;   }   int main() {     cin >> L >> R;     no[1][1] = no[2][2] = no[3][3] = no[4][4] = no[1][2] = no[3][4] = no[2][1] =         no[4][3] = 1;     cout << (calc(R) - calc(L - 1) + MOD) % MOD << endl;     return 0;   }   