#include <bits/stdc++.h>
using namespace std;
template <class T>
inline T bigmod(T p, T e, T M) {
  long long ret = 1;
  for (; e > 0; e >>= 1) {
    if (e & 1) ret = (ret * p) % M;
    p = (p * p) % M;
  }
  return (T)ret;
}
template <class T>
inline T gcd(T a, T b) {
  if (b == 0) return a;
  return gcd(b, a % b);
}
template <class T>
inline T modinverse(T a, T M) {
  return bigmod(a, M - 2, M);
}
long long dp[2001][2001];
long long go(int c, int v) {
  if (v > c) return 0;
  if (c == 0) return 1;
  long long &ret = dp[c][v];
  if (ret != -1) return ret;
  ret = 0;
  ret = (ret + go(c - 1, v + 1)) % 1000000007ll;
  if (v > 0) ret = (ret + go(c - 1, v - 1)) % 1000000007ll;
  return ret;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  string s;
  int n, m;
  cin >> n >> m >> s;
  int mn = 0, tot = 0;
  for (int i = (0); i < (s.size()); ++i) {
    if (s[i] == '(')
      tot++;
    else
      tot--;
    mn = min(mn, tot);
  }
  memset(dp, -1, sizeof dp);
  n -= m;
  long long res = 0;
  for (int i = 0; i <= n; i++) {
    for (int j = -mn; j <= n; j++) {
      res = (res + go(i, j) * go(n - i, j + tot)) % 1000000007ll;
    }
  }
  cout << res << endl;
}
