#include "bits/stdc++.h"
using namespace std;
#define rep(i,n) for(int (i)=0;(i)<(int)(n);++(i))
#define rer(i,l,u) for(int (i)=(int)(l);(i)<=(int)(u);++(i))
#define reu(i,l,u) for(int (i)=(int)(l);(i)<(int)(u);++(i))
static const int INF = 0x3f3f3f3f; static const long long INFL = 0x3f3f3f3f3f3f3f3fLL;
typedef vector<int> vi; typedef pair<int, int> pii; typedef vector<pair<int, int> > vpii; typedef long long ll;
template<typename T, typename U> static void amin(T &x, U y) { if (y < x) x = y; }
template<typename T, typename U> static void amax(T &x, U y) { if (x < y) x = y; }


template<int MOD>
struct ModInt {
	static const int Mod = MOD;
	unsigned x;
	ModInt() : x(0) { }
	ModInt(signed sig) { int sigt = sig % MOD; if (sigt < 0) sigt += MOD; x = sigt; }
	ModInt(signed long long sig) { int sigt = sig % MOD; if (sigt < 0) sigt += MOD; x = sigt; }
	int get() const { return (int)x; }

	ModInt &operator+=(ModInt that) { if ((x += that.x) >= MOD) x -= MOD; return *this; }
	ModInt &operator-=(ModInt that) { if ((x += MOD - that.x) >= MOD) x -= MOD; return *this; }
	ModInt &operator*=(ModInt that) { x = (unsigned long long)x * that.x % MOD; return *this; }

	ModInt operator+(ModInt that) const { return ModInt(*this) += that; }
	ModInt operator-(ModInt that) const { return ModInt(*this) -= that; }
	ModInt operator*(ModInt that) const { return ModInt(*this) *= that; }
};
typedef ModInt<1000000007> mint;

int main() {
	int N;
	while (~scanf("%d", &N)) {
		vector<int> xs(N);
		for (int i = 0; i < N; ++ i)
			scanf("%d", &xs[i]);
		mint ans;
		rep(rm, 2) rep(lm, 2) {
			vector<mint> dp, ndp(4);
			ndp[rm << 1 | lm] += 1;
			rep(i, N) {
				dp.swap(ndp);
				ndp.assign(4, mint());
				rep(l, 2) rep(c, 2) {
					mint x = dp[l << 1 | c];
					if (x.x == 0) continue;
					rep(r, 2) {
						if ((110 >> (l << 2 | c << 1 | r) & 1) != xs[i])
							continue;
						ndp[c << 1 | r] += x;
					}
				}
			}
			ans += ndp[rm << 1 | lm];
		}
		printf("%d\n", ans.get());
	}
	return 0;
}