#include<iostream>
#include<cstdio>
using namespace std;
#define LL long long
const int MOD=1e9+7;
int n,k;
LL dp[510][510][6];
string s;
bool match(int a,int b){
	return (s[a]=='('||s[a]=='?')&&(s[b]==')'||s[b]=='?');
}
int main(){
	cin>>n>>k>>s;
	s=" "+s;
	for(int i=1;i<=n;i++){
		dp[i][i-1][0]=1;
	}
	for(int l=1;l<=n;l++){
		for(int i=1;i<=n-l+1;i++){
			int j=i+l-1;
			if(l<=k) dp[i][j][0]=dp[i][j-1][0]&&(s[j]=='*'||s[j]=='?');
			if(l>=2){
				if(match(i,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])%MOD;
				}
				for(int k=i;k<j;k++){
					dp[i][j][2]=(dp[i][k][3]*dp[k+1][j][0]+dp[i][j][2])%MOD;
					dp[i][j][3]=((dp[i][k][2]+dp[i][k][3])*dp[k+1][j][1]+dp[i][j][3])%MOD;
					dp[i][j][4]=((dp[i][k][4]+dp[i][k][5])*dp[k+1][j][1]+dp[i][j][4])%MOD;
					dp[i][j][5]=(dp[i][k][4]*dp[k+1][j][0]+dp[i][j][5])%MOD;
				}
				dp[i][j][5]=(dp[i][j][5]+dp[i][j][0])%MOD;
				dp[i][j][3]=(dp[i][j][3]+dp[i][j][1])%MOD;
			}
		}
	}
	printf("%lld",dp[1][n][3]);
	return 0;
}

求助