std::vector<std::vector<int>> sq_mul(const std::vector<std::vector<int>> &A, const std::vector<std::vector<int>> &B, long long m) {
    std::vector<std::vector<int>> C(A.size(), std::vector<int>(B[0].size()));
    for(int i = 0; i < A.size(); ++i) {
        for(int j = 0; j < B[0].size(); ++j) {
            int s = 0;
            for(int k = 0; k < B.size(); ++k) {
                s += A[i][k] * B[k][j];
                s %= m;
            }
            C[i][j] = s;
        }
    }
    return C;
}

int lin_rec(std::vector<std::vector<int>> M, const std::vector<int>& M0, int N, long long m) {
    if(N < M0.size()) return M0[N];
    N -= M0.size() - 1;
    std::vector<std::vector<int>> R(M0.size(), std::vector<int>(M0.size()));
    for(int i = 0; i < M0.size(); ++i) {
        R[i][i] = 1;
    }
    while(N) {
        if(N & 1) {
            R = sq_mul(R, M, m);
        }
        N >>= 1;
        M = sq_mul(M, M, m);
    }
    
    int s = 0;
    for(int j = 0; j < M0.size(); ++j) {
        s += R[M0.size() - 1][j] * M0[j];
        s %= m;
    }
    return s;
}


long long stepPerms(long long n) {
    // 1, 2, 3
    // Fn = Fn-1 + Fn-2 + Fn-3
    std::vector<std::vector<int>> M = {{0, 1, 0}, {0, 0, 1}, {1, 1, 1}};
    std::vector<int> M0 = {1, 1, 2};
    return lin_rec(M, M0, n, 1e10 + 7);
}