#include <bits/stdc++.h>
using namespace std;
int n, m, k;
string str;
long long dp[2007][2007] = {0}, ans = 0;
int main() {
  scanf("%d%d", &n, &m);
  k = n - m;
  cin >> str;
  dp[0][0] = dp[1][1] = 1;
  for (int i = 2; i <= k; i++)
    for (int j = 0; j <= i; j++)
      dp[i][j] =
          (dp[i - 1][j + 1] + (j > 0 ? dp[i - 1][j - 1] : 0)) % 1000000007ULL;
  int minx = 0x7FFFFFF, sum = 0;
  for (int i = 0; i < m; i++) {
    if (str[i] == '(')
      sum += 1;
    else
      sum -= 1;
    minx = min(minx, sum);
  }
  minx = max(-minx, 0);
  for (int i = 0; i <= k; i++)
    for (int j = minx; j <= i && sum + j <= k - i; j++) {
      ans += (dp[i][j] * dp[k - i][sum + j]) % 1000000007ULL;
      ans %= 1000000007ULL;
    }
  cout << ans << endl;
  return 0;
}
