#define _USE_MATH_DEFINES
#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <complex>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
#include <iterator>
using namespace std;

const int NEXT_CELL[] = {0, 1, 1, 1, 0, 1, 1, 0};
const int MOD = 1000000007;

int main()
{
    int n;
    cin >> n;
    vector<int> e(n);
    for(int i=0; i<n; ++i)
        cin >> e[i];

    int ans = 0;
    for(int init=0; init<4; ++init){
        vector<int> dp(4, 0);
        dp[init] = 1;
        for(int i=0; i<n; ++i){
            vector<int> nextDp(4, 0);
            for(int a=0; a<4; ++a){
                for(int j=0; j<2; ++j){
                    int b = (a << 1) | j;
                    if(NEXT_CELL[b] == e[i]){
                        b &= 3;
                        nextDp[b] += dp[a];
                        nextDp[b] %= MOD;
                    }
                }
            }
            dp.swap(nextDp);
        }
        ans += dp[init];
        ans %= MOD;
    }
    cout << ans << endl;

    return 0;
}