func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long MOD = 1e9 + 7;   vector<vector<long long>> mul(vector<vector<long long>> A,                                 vector<vector<long long>> B) {     int n = A.size();     vector<vector<long long>> res(n, vector<long long>(n));     for (int i = 0; i < n; i++) {       for (int j = 0; j < n; j++) {         for (int k = 0; k < n; k++) {           res[i][j] = (res[i][j] + A[i][k] * B[k][j]) % MOD;         }       }     }     return res;   }   vector<vector<long long>> mexp(vector<vector<long long>> M, long long e) {     if (e == 1) return M;     if (e % 2) return mul(M, mexp(M, e - 1));     vector<vector<long long>> R = mexp(M, e / 2);     return mul(R, R);   }   int main() {     long long n, m;     cin >> n >> m;     if (m > n) {       cout << 1 << endl;       return 0;     }     vector<vector<long long>> M(m, vector<long long>(m));     M[0][0] = M[0][m - 1] = 1;     for (int i = 1; i < m; i++) M[i][i - 1] = 1;     vector<vector<long long>> R = mexp(M, n - m + 1);     long long res = 0;     for (int i = 0; i < m; i++) res = (res + R[0][i]) % MOD;     cout << res << endl;   }   