b.cpp

#include <iostream>
#include <vector>

using namespace std;
#define ull long long

typedef vector<vector<ull>> Matrix;
const ull MOD = 1000000007;

Matrix multiply(const Matrix& A, const Matrix& B) {
    ull n = A.size();
    Matrix result(n, vector<ull>(n, 0));
    for (ull i = 0; i < n; ++i) {
        for (ull j = 0; j < n; ++j) {
            for (ull k = 0; k < n; ++k) {
                result[i][j] =
                    (result[i][j] + (ull)A[i][k] * B[k][j] % MOD) % MOD;
            }
        }
    }
    return result;
}

Matrix matrixPower(Matrix M, ull exp) {
    ull n = M.size();
    Matrix result(n, vector<ull>(n, 0));
    for (ull i = 0; i < n; ++i) {
        result[i][i] = 1;
    }

    while (exp > 0) {
        if (exp % 2 == 1) {
            result = multiply(result, M);
        }
        M = multiply(M, M);
        exp /= 2;
    }
    return result;
}

ull matrixExponentiation(ull N) {
    Matrix M = {{0, 2, 1, 0}, {1, 0, 0, 1}, {1, 0, 0, 0}, {0, 1, 0, 0}};
    vector<ull> V2 = {0, 1, 1, 0};

    if (N == 1) {
        return V2[0];
    }

    Matrix M_power = matrixPower(M, N - 1);
    ull result = 0;
    for (ull i = 0; i < 4; ++i) {
        result = (result + (ull)M_power[0][i] * V2[i] % MOD) % MOD;
    }

    return result;
}

int main() {
    ull N;
    cin >> N;
    cout << matrixExponentiation(N);
}