#include <bits/stdc++.h>
using namespace std;
long long dp[2010][2010];
string s;
int n, m;
int main() {
  memset((dp), (0), sizeof(dp));
  scanf("%d%d", &n, &m);
  cin >> s;
  dp[0][0] = 1;
  for (int i = 1; i <= n - m; i++) {
    dp[i][0] = dp[i - 1][1] % 1000000007;
    for (int j = 1; j <= i; j++) {
      dp[i][j] = (dp[i - 1][j - 1] + dp[i - 1][j + 1]) % 1000000007;
    }
  }
  int mn = 0x3f3f3f3f, sum = 0;
  for (int i = 0; i < s.size(); i++) {
    if (s[i] == '(')
      sum++;
    else
      sum--;
    mn = min(mn, sum);
  }
  long long ans = 0;
  for (int i = 0; i <= n - m; i++) {
    for (int j = 0; j <= i; j++) {
      if (j + mn >= 0 && j + sum <= n - m - i) {
        ans += (dp[i][j] * dp[n - m - i][j + sum]) % 1000000007;
        ans %= 1000000007;
      }
    }
  }
  printf("%I64d\n", ans % 1000000007);
  return 0;
}
