#include<bits/stdc++.h>
using namespace std;
#define int long long
#define LL __int128
#define reg register 
const int P=1e9+7,N=505;

int dp[N][N][10],n,k;
char s[N];

signed main(){
	ios::sync_with_stdio(0);
	cin>>n>>k>>s+1;
	for(reg int i=1;i<=n;i++){
		dp[i][i-1][0]=1;
	}
	for(reg int l=1;l<=n;l++){
		for(reg int i=1;i+l-1<=n;i++){
			reg int j=i+l-1;
			if(l<=k)(dp[i][j][0]=dp[i][j-1][0]&&(s[j]=='*' || s[j]=='?'))%P;
			if(l>=2){
				if((s[i]=='(' || s[i]=='*') && (s[i]=='(' || s[j]=='*'))dp[i][j][1]=(dp[i+1][j-1][0]+dp[i+1][j-1][2]+dp[i+1][j-1][3]+dp[i+1][j-1][4])%P;
				for(reg int k=i;k<j;k++){
                    (dp[i][j][2]+=dp[i][k][3]*dp[k+1][j][0])%P;
                    (dp[i][j][3]+=(dp[i][k][2]+dp[i][k][3])*dp[k+1][j][1])%P;
                    (dp[i][j][4]+=(dp[i][k][4]+dp[i][k][5])*dp[k+1][j][1])%P;
                    (dp[i][j][5]+=dp[i][k][4]*dp[k+1][j][0])%P;
				}
				(dp[i][j][5]+=dp[i][j][0])%P;
				(dp[i][j][3]+=dp[i][j][0])%P;
			}
		}
	}
	cout<<dp[1][n][3];
	return 0;
}