#include "bits/stdc++.h"
using namespace std;

#define DEBUG(x) cout<<#x<<": "<<x<<endl;
#define DEBUG_VEC(v) cout<<#v<<":";for(int i=0;i<v.size();i++) cout<<" "<<v[i]; cout<<endl

typedef long long ll;
#define vi vector<int>
#define vl vector<ll>
#define vii vector< vector<int> >
#define vll vector< vector<ll> >
#define vs vector<string>
#define pii pair<int,int>
#define pis pair<int,string>
#define psi pair<string,int>
#define pll pair<ll,ll>
#define fi first
#define se second
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define rep1(i,n) for(int i=1;i<=(int)(n);i++)
#define all(c) c.begin(),c.end()
const int inf = 1000000001;
const ll INF = 2e18;
const ll MOD = 1000000007;
const ll mod = 1000000009;
const double pi = 3.14159265358979323846;
#define Sp(p) cout<<setprecision(15)<< fixed<<p<<endl;
int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 };
int dx2[8] = { 1,1,0,-1,-1,-1,0,1 }, dy2[8] = { 0,1,1,1,0,-1,-1,-1 };

vector<vll> dp(2020, vll(2, vl(2)));
int n;
string s;

int g(int a, int b, int c) {
	if (b == 0 && c == 0) return 0;
	if (a*b*c == 1) return 0;
	return 1;
}

ll f(int v0, int v1) {
	rep(i, n + 1) {
		rep(j, 2) {
			rep(k, 2) {
				dp[i][j][k] = 0;
			}
		}
	}
	dp[2][v0][v1] = 1;
	for (int i = 2; i < n; i++) {
		rep(a, 2) {
			rep(b, 2) {
				rep(c, 2) {
					if (g(a, b, c) + '0' == s[i - 1]) {
						(dp[i + 1][b][c] += dp[i][a][b]) %= MOD;
					}
				}
			}
		}
	}
	ll res = 0;
	rep(a, 2) {
		rep(b, 2) {
			if (g(a, b, v0) + '0' == s[n - 1] && g(b, v0, v1) + '0' == s[0]) {
				(res += dp[n][a][b]) %= MOD;
			}
		}
	}
	return res;
}

int main() {
	cin >> n;
	rep(i, n) {
		char c;
		cin >> c;
		s.push_back(c);
	}
	ll ans = 0;
	rep(v0, 2) {
		rep(v1, 2) {
			(ans += f(v0, v1)) %= MOD;
		}
	}
	cout << ans << endl;
}