#include <bits/stdc++.h>
using namespace std;
typedef long long lint;
typedef pair<lint, int> pi;
const int MAXN = 5005;
const int mod = 1e9 + 7;

namespace fft{
	typedef complex<double> base;
	void fft(vector<base> &a, bool inv){
		int n = a.size(), j = 0;
		vector<base> roots(n/2);
		for(int i=1; i<n; i++){
			int bit = (n >> 1);
			while(j >= bit){
				j -= bit;
				bit >>= 1;
			}
			j += bit;
			if(i < j) swap(a[i], a[j]);
		}
		double ang = 2 * acos(-1) / n * (inv ? -1 : 1);
		for(int i=0; i<n/2; i++){
			roots[i] = base(cos(ang * i), sin(ang * i));
		}
		/* In NTT, let prr = primitive root. Then,
		int ang = ipow(prr, (mod - 1) / n);
		if(inv) ang = ipow(ang, mod - 2);
		for(int i=0; i<n/2; i++){
			roots[i] = (i ? (1ll * roots[i-1] * ang % mod) : 1);
		}
		Others are same. If there is /= n, do *= ipow(n, mod - 2).
		In XOR convolution, roots[*] = 1.
		*/
		for(int i=2; i<=n; i<<=1){
			int step = n / i;
			for(int j=0; j<n; j+=i){
				for(int k=0; k<i/2; k++){
					base u = a[j+k], v = a[j+k+i/2] * roots[step * k];
					a[j+k] = u+v;
					a[j+k+i/2] = u-v;
				}
			}
		}
		if(inv) for(int i=0; i<n; i++) a[i] /= n;
	}

	vector<lint> multiply(vector<lint> &v, vector<lint> &w){
		vector<base> fv(v.begin(), v.end()), fw(w.begin(), w.end());
		int n = 2; while(n < v.size() + w.size()) n <<= 1;
		fv.resize(n); fw.resize(n);
		fft(fv, 0); fft(fw, 0);
		for(int i=0; i<n; i++) fv[i] *= fw[i];
		fft(fv, 1);
		vector<lint> ret(n);
		for(int i=0; i<n; i++) ret[i] = (lint)round(fv[i].real());
		return ret;
	}
	vector<lint> multiply(vector<lint> &v, vector<lint> &w, lint mod){
		int n = 2; while(n < v.size() + w.size()) n <<= 1;
		vector<base> v1(n), v2(n), r1(n), r2(n);
		for(int i=0; i<v.size(); i++){
			v1[i] = base(v[i] >> 15, v[i] & 32767);
		}
		for(int i=0; i<w.size(); i++){
			v2[i] = base(w[i] >> 15, w[i] & 32767);
		}
		fft(v1, 0);
		fft(v2, 0);
		for(int i=0; i<n; i++){
			int j = (i ? (n - i) : i);
			base ans1 = (v1[i] + conj(v1[j])) * base(0.5, 0);
			base ans2 = (v1[i] - conj(v1[j])) * base(0, -0.5);
			base ans3 = (v2[i] + conj(v2[j])) * base(0.5, 0);
			base ans4 = (v2[i] - conj(v2[j])) * base(0, -0.5);
			r1[i] = (ans1 * ans3) + (ans1 * ans4) * base(0, 1);
			r2[i] = (ans2 * ans3) + (ans2 * ans4) * base(0, 1);
		}
		fft(r1, 1);
		fft(r2, 1);
		vector<lint> ret(n);
		for(int i=0; i<n; i++){
			lint av = (lint)round(r1[i].real());
			lint bv = (lint)round(r1[i].imag()) + (lint)round(r2[i].real());
			lint cv = (lint)round(r2[i].imag());
			av %= mod, bv %= mod, cv %= mod;
			ret[i] = (av << 30) + (bv << 15) + cv;
			ret[i] %= mod;
			ret[i] += mod;
			ret[i] %= mod;
		}
		return ret;
	}
}

lint cat[MAXN], pwr[MAXN];
lint dp[MAXN][MAXN], em[MAXN];

int main(){
	int n, m; string s; cin >> n >> s; m = s.size();
	cat[0] = pwr[0] = 1;
	for(int i=1; i<=n; i++){
		for(int j=0; j<i; j++) cat[i] += cat[j] * cat[i-j-1] % mod;
		pwr[i] = pwr[i-1] * 2 % mod;
		cat[i] %= mod;
	}
	em[0] = 1;
	for(int i=1; i<=n; i++){
		em[i] = em[i-1];
		for(int j=i-2; j>=0; j-=2){
			int l = (i - j) / 2;
			em[i] += em[j] * (pwr[l] * cat[l-1] % mod) % mod;
		}
		em[i] %= mod;
	}
	n -= m;
	dp[0][0] = 1;
	vector<lint> piv(n/2+1), v(n/2+1);
	v[0] = 1;
	for(int i=0; i<=n/2; i++){
		piv[i] = cat[i];
	}
	while(m){
		if(m & 1) v = fft::multiply(v, piv, mod);
		piv = fft::multiply(piv, piv, mod);
		v.resize(n / 2 + 1);
		piv.resize(n / 2 + 1);
		m >>= 1;
	}
	lint ans = 0;
	for(int i=0; i<=n; i++){
		if(i % 2 == 0){
			ans += v[i/2] * (em[n-i] * pwr[i / 2] % mod) % mod;
		}
	}
	cout << ans % mod << endl;
}


Measured memory_bytes: 1136