#include <bits/stdc++.h>
#define rep(i, n) for (lli i = 0; i < (n); i++)
#define rrep(i, n) for (lli i = (n)-1; i >= 0; i--)
using namespace std;
using lli = long long int;
template <signed M, unsigned T>
struct mod_int {
    constexpr static signed MODULO = M;
    constexpr static unsigned TABLE_SIZE = T;

    signed x;

    mod_int() : x(0) {}

    mod_int(long long y) : x(static_cast<signed>(y >= 0 ? y % MODULO : MODULO - (-y) % MODULO)) {}

    mod_int(int y) : x(y >= 0 ? y % MODULO : MODULO - (-y) % MODULO) {}

    mod_int& operator+=(const mod_int& rhs)
    {
        if ((x += rhs.x) >= MODULO)
            x -= MODULO;
        return *this;
    }

    mod_int& operator-=(const mod_int& rhs)
    {
        if ((x += MODULO - rhs.x) >= MODULO)
            x -= MODULO;
        return *this;
    }

    mod_int& operator*=(const mod_int& rhs)
    {
        x = static_cast<signed>(1LL * x * rhs.x % MODULO);
        return *this;
    }

    mod_int& operator/=(const mod_int& rhs)
    {
        x = static_cast<signed>((1LL * x * rhs.inv().x) % MODULO);
        return *this;
    }

    mod_int operator-() const { return mod_int(-x); }

    mod_int operator+(const mod_int& rhs) const { return mod_int(*this) += rhs; }

    mod_int operator-(const mod_int& rhs) const { return mod_int(*this) -= rhs; }

    mod_int operator*(const mod_int& rhs) const { return mod_int(*this) *= rhs; }

    mod_int operator/(const mod_int& rhs) const { return mod_int(*this) /= rhs; }

    bool operator<(const mod_int& rhs) const { return x < rhs.x; }

    mod_int inv() const
    {
        assert(x != 0);
        if (x <= static_cast<signed>(TABLE_SIZE)) {
            if (_inv[1].x == 0)
                prepare();
            return _inv[x];
        } else {
            signed a = x, b = MODULO, u = 1, v = 0, t;
            while (b) {
                t = a / b;
                a -= t * b;
                std::swap(a, b);
                u -= t * v;
                std::swap(u, v);
            }
            return mod_int(u);
        }
    }

    mod_int pow(long long t) const
    {
        assert(!(x == 0 && t == 0));
        mod_int e = *this, res = mod_int(1);
        for (; t; e *= e, t >>= 1)
            if (t & 1)
                res *= e;
        return res;
    }

    mod_int fact()
    {
        if (_fact[0].x == 0)
            prepare();
        return _fact[x];
    }

    mod_int inv_fact()
    {
        if (_fact[0].x == 0)
            prepare();
        return _inv_fact[x];
    }

    mod_int choose(mod_int y)
    {
        assert(y.x <= x);
        return this->fact() * y.inv_fact() * mod_int(x - y.x).inv_fact();
    }

    static mod_int _inv[TABLE_SIZE + 1];

    static mod_int _fact[TABLE_SIZE + 1];

    static mod_int _inv_fact[TABLE_SIZE + 1];

    static void prepare()
    {
        _inv[1] = 1;
        for (int i = 2; i <= (int)TABLE_SIZE; ++i) {
            _inv[i] = 1LL * _inv[MODULO % i].x * (MODULO - MODULO / i) % MODULO;
        }
        _fact[0] = 1;
        for (unsigned i = 1; i <= TABLE_SIZE; ++i) {
            _fact[i] = _fact[i - 1] * int(i);
        }
        _inv_fact[TABLE_SIZE] = _fact[TABLE_SIZE].inv();
        for (int i = (int)TABLE_SIZE - 1; i >= 0; --i) {
            _inv_fact[i] = _inv_fact[i + 1] * (i + 1);
        }
    }
};

template <int M, unsigned F>
std::ostream& operator<<(std::ostream& os, const mod_int<M, F>& rhs)
{
    return os << rhs.x;
}

template <int M, unsigned F>
std::istream& operator>>(std::istream& is, mod_int<M, F>& rhs)
{
    long long s;
    is >> s;
    rhs = mod_int<M, F>(s);
    return is;
}

template <int M, unsigned F>
mod_int<M, F> mod_int<M, F>::_inv[TABLE_SIZE + 1];

template <int M, unsigned F>
mod_int<M, F> mod_int<M, F>::_fact[TABLE_SIZE + 1];

template <int M, unsigned F>
mod_int<M, F> mod_int<M, F>::_inv_fact[TABLE_SIZE + 1];

template <int M, unsigned F>
bool operator==(const mod_int<M, F>& lhs, const mod_int<M, F>& rhs)
{
    return lhs.x == rhs.x;
}

template <int M, unsigned F>
bool operator!=(const mod_int<M, F>& lhs, const mod_int<M, F>& rhs)
{
    return !(lhs == rhs);
}

const int MF = 100005;  //割り算しないなら
const int MOD = 1000000007;

using mint = mod_int<MOD, MF>;

mint binom(int n, int r)
{
    return (r < 0 || r > n || n < 0) ? 0 : mint(n).choose(r);
}

mint fact(int n)
{
    return mint(n).fact();
}

mint inv_fact(int n)
{
    return mint(n).inv_fact();
}
int main()
{
  int n;
  cin >> n;
  mint ans = 1;
  int a[3] = {0, 0, 0};
  for(int i = 0;i<n;i++){
    int b;
    cin >> b;
    int cnt = 0;
    rep(j, 3){
      if(a[j] == b){
        cnt++;
      }
    }
    rep(j, 3){
      if(a[j] == b){
        a[j]++;
        break;
      }
    }
    ans *= cnt;
  }
  cout << ans << endl;
}


Measured memory_bytes: 1536