#include <iostream>
#include <cstdio>

using namespace std;
typedef long long i64;
const int MOD = 1000000007;

int n, k;
char s[505];
i64 f[505][505][6];
// f[0]: **
// f[1]: (..)
// f[2]: (..)**
// f[3]: (..)..(..) 包含 1
// f[4]: **(..) 
// f[5]: **(..)** 包含 0 

int main(void)
{
	scanf("%d%d%s", &n, &k, s + 1);
	for (int i = 1; i <= n; ++i) f[i][i-1][0] = 1;
	for (int len = 1; len <= n; ++len)
		for (int i = 1; i <= n - len + 1; ++i) {
			int j = i + len - 1;
			if (len <= k) f[i][j][0] = f[i][j-1][0] && (s[j] == '*' || s[j] == '?');
			if (len >= 2) {
				if ((s[i] == '(' || s[i] == '?') && (s[j] == ')' || s[j] == '?'))
					f[i][j][1] = (f[i+1][j-1][0] + f[i+1][j-1][2] + f[i+1][j-1][3] + f[i+1][j-1][4]) % MOD;
				for (int k = i; k < j; ++k) {
					f[i][j][2] = (f[i][j][2] + f[i][k][3] * f[k+1][j][0]) % MOD;
					f[i][j][3] = (f[i][j][3] + (f[i][k][2]+f[i][k][3]) * f[k+1][j][1]) % MOD;
					f[i][j][4] = (f[i][j][4] + (f[i][k][4]+f[i][k][5]) * f[k+1][j][1]) % MOD;
					f[i][j][5] = (f[i][j][5] + f[i][k][4] * f[k+1][j][0]) % MOD;
				}
			}
			f[i][j][5] = (f[i][j][5] + f[i][j][0]) % MOD;
			f[i][j][3] = (f[i][j][3] + f[i][j][1]) % MOD;
		}
	printf("%lld\n", f[1][n][3]);
	return 0;
}