#include<iostream>

#include<cstdio>

#include<cstring>

#include<string>

#include<algorithm>

#include<cctype>

#include<cmath>

#include<cstdlib>

#include<ctime>

#include<queue>

#include<vector>

#include<set>

#include<map>

#include<stack>

using namespace std;

const int mod = 1e9+;

int dp[][],n,m;

char s[];

inline int pw(int x,int p){

    x%=mod;

    int res=;

    while(p){

      if(p&)res=(long long)res*x%mod;

      x=(long long)x*x%mod;

      p>>=;

    }

    return res;

}

int main(){

    int i,j,k;

    scanf("%d",&n);

    scanf("%s",s);

    m=strlen(s);

    dp[][]=;

    for(i=;i<=n;i++)

      for(j=;j<=i;j++){

          if(j)dp[i][j]=(dp[i][j]+dp[i-][j-]*)%mod;

          if(j==)dp[i][j]=(dp[i][j]+dp[i-][j])%mod;

          dp[i][j]=(dp[i][j]+dp[i-][j+])%mod;

      }

    int Ans=(long long)dp[n][m]*pw(pw(,m),mod-)%mod;

    printf("%d\n",Ans);

    return ;

}