#include <bits/stdc++.h>
using namespace std;
long long mod = (long long)1000000007;
long long n, m;
string s;
long long bal, mn;
long long dp[5005][5005];
long long ans;
int main() {
  ios_base::sync_with_stdio(0);
  cin >> n >> m;
  cin >> s;
  for (int i = 0; i < (int)s.size(); ++i) {
    if (s[i] == '(')
      ++bal;
    else
      --bal;
    mn = min(bal, mn);
  }
  dp[0][0] = 1;
  for (int i = 1; i <= n - m; ++i)
    for (int j = 0; j <= i; ++j)
      dp[i][j] = (dp[i - 1][j + 1] + (j ? dp[i - 1][j - 1] : 0)) % mod;
  for (int i = 0; i <= n - m; ++i)
    for (int j = -mn; j <= i; ++j) {
      if (bal + j > 5000) continue;
      long long cur = (dp[i][j] * dp[n - m - i][bal + j]) % mod;
      ans = (ans + cur) % mod;
    }
  cout << ans;
  return 0;
}
