#include <iostream>
#include <numeric>
#include <vector>
#include <set>

template <class T>
std::vector<T> vec(int len, T elem) { return std::vector<T>(len, elem); }

template <int MOD>
struct ModInt {
    using lint = long long;
    int val;

    // constructor
    ModInt(lint v = 0) : val(v % MOD) {
        if (val < 0) val += MOD;
    };

    // unary operator
    ModInt operator+() const { return ModInt(val); }
    ModInt operator-() const { return ModInt(MOD - val); }
    ModInt inv() const { return this->pow(MOD - 2); }

    // arithmetic
    ModInt operator+(const ModInt& x) const { return ModInt(*this) += x; }
    ModInt operator-(const ModInt& x) const { return ModInt(*this) -= x; }
    ModInt operator*(const ModInt& x) const { return ModInt(*this) *= x; }
    ModInt operator/(const ModInt& x) const { return ModInt(*this) /= x; }
    ModInt pow(lint n) const {
        auto x = ModInt(1);
        auto b = *this;
        while (n > 0) {
            if (n & 1) x *= b;
            n >>= 1;
            b *= b;
        }
        return x;
    }

    // compound assignment
    ModInt& operator+=(const ModInt& x) {
        if ((val += x.val) >= MOD) val -= MOD;
        return *this;
    }
    ModInt& operator-=(const ModInt& x) {
        if ((val -= x.val) < 0) val += MOD;
        return *this;
    }
    ModInt& operator*=(const ModInt& x) {
        val = lint(val) * x.val % MOD;
        return *this;
    }
    ModInt& operator/=(const ModInt& x) { return *this *= x.inv(); }

    // compare
    bool operator==(const ModInt& b) const { return val == b.val; }
    bool operator!=(const ModInt& b) const { return val != b.val; }
    bool operator<(const ModInt& b) const { return val < b.val; }
    bool operator<=(const ModInt& b) const { return val <= b.val; }
    bool operator>(const ModInt& b) const { return val > b.val; }
    bool operator>=(const ModInt& b) const { return val >= b.val; }

    // I/O
    friend std::istream& operator>>(std::istream& is, ModInt& x) noexcept { return is >> x.val; }
    friend std::ostream& operator<<(std::ostream& os, const ModInt& x) noexcept { return os << x.val; }
};

constexpr int MOD = 1000000007;
using mint = ModInt<MOD>;

const std::vector<std::set<int>>
    nxts{{0b000, 0b100, 0b111},
         {0b001, 0b010, 0b011, 0b101, 0b110}};

void solve() {
    int n;
    std::cin >> n;

    auto dps = vec(4, vec(4, mint(0)));
    for (int b = 0; b < 4; ++b) dps[b][b] = 1;
    auto ndps = dps;

    for (int i = 0; i < n - 2; ++i) {
        int p;
        std::cin >> p;

        for (auto& v : ndps) std::fill(v.begin(), v.end(), 0);
        for (int c = 0; c < 4; ++c) {
            auto& dp = dps[c];
            auto& ndp = ndps[c];

            for (auto b : nxts[p]) {
                int pb = b >> 1;
                int nb = b & 3;
                ndp[nb] += dp[pb];
            }
        }

        dps = ndps;
    }

    int p1, p2;
    std::cin >> p1 >> p2;

    mint ans = 0;
    for (int sb = 0; sb < 4; ++sb) {
        for (int lb = 0; lb < 4; ++lb) {
            int b = (lb << 2) | sb;
            if (nxts[p1].count(b >> 1) && nxts[p2].count(b & 7)) {
                ans += dps[sb][lb];
            }
        }
    }

    std::cout << ans << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}