using System; using System.Linq; using CompLib.Util; using System.Threading; using System.IO; using System.Collections.Generic; using System.Text; using CompLib.Mathematics; public class Program { public void Solve() { var sc = new Scanner(); int n = sc.NextInt(); int m = n / 2; string s = sc.Next(); var dp = new ModInt[n + 1, n + 1]; dp[0, 0] = 1; int cnt = 0; for (int i = 0; i < n; i++) { for (int j = 0; j <= n && cnt - j >= 0; j++) { int k = cnt - j; if (s[i] == '(') { dp[i + 1, j + 1] += dp[i, j]; dp[i + 1, j] += dp[i, j]; } else { if (j - 1 >= 0) dp[i + 1, j - 1] += dp[i, j]; if (k - 1 >= 0) dp[i + 1, j] += dp[i, j]; } } cnt += s[i] == '(' ? 1 : -1; } Console.WriteLine(dp[n, 0]); } public static void Main(string[] args) => new Program().Solve(); // public static void Main(string[] args) => new Thread(new Program().Solve, 1 << 27).Start(); } // https://bitbucket.org/camypaper/complib namespace CompLib.Mathematics { #region ModInt /// /// [0,) までの値を取るような数 /// public struct ModInt { /// /// 剰余を取る値. /// // public const long Mod = (int)1e9 + 7; public const long Mod = 998244353; /// /// 実際の数値. /// public long num; /// /// 値が であるようなインスタンスを構築します. /// /// インスタンスが持つ値 /// パフォーマンスの問題上,コンストラクタ内では剰余を取りません.そのため, ∈ [0,) を満たすような を渡してください.このコンストラクタは O(1) で実行されます. public ModInt(long n) { num = n; } /// /// このインスタンスの数値を文字列に変換します. /// /// [0,) の範囲内の整数を 10 進表記したもの. public override string ToString() { return num.ToString(); } public static ModInt operator +(ModInt l, ModInt r) { l.num += r.num; if (l.num >= Mod) l.num -= Mod; return l; } public static ModInt operator -(ModInt l, ModInt r) { l.num -= r.num; if (l.num < 0) l.num += Mod; return l; } public static ModInt operator *(ModInt l, ModInt r) { return new ModInt(l.num * r.num % Mod); } public static implicit operator ModInt(long n) { n %= Mod; if (n < 0) n += Mod; return new ModInt(n); } /// /// 与えられた 2 つの数値からべき剰余を計算します. /// /// べき乗の底 /// べき指数 /// 繰り返し二乗法により O(N log N) で実行されます. public static ModInt Pow(ModInt v, long k) { return Pow(v.num, k); } /// /// 与えられた 2 つの数値からべき剰余を計算します. /// /// べき乗の底 /// べき指数 /// 繰り返し二乗法により O(N log N) で実行されます. public static ModInt Pow(long v, long k) { long ret = 1; for (k %= Mod - 1; k > 0; k >>= 1, v = v * v % Mod) if ((k & 1) == 1) ret = ret * v % Mod; return new ModInt(ret); } /// /// 与えられた数の逆元を計算します. /// /// 逆元を取る対象となる数 /// 逆元となるような値 /// 法が素数であることを仮定して,フェルマーの小定理に従って逆元を O(log N) で計算します. public static ModInt Inverse(ModInt v) { return Pow(v, Mod - 2); } } #endregion #region Binomial Coefficient public class BinomialCoefficient { public ModInt[] fact, ifact; public BinomialCoefficient(int n) { fact = new ModInt[n + 1]; ifact = new ModInt[n + 1]; fact[0] = 1; for (int i = 1; i <= n; i++) fact[i] = fact[i - 1] * i; ifact[n] = ModInt.Inverse(fact[n]); for (int i = n - 1; i >= 0; i--) ifact[i] = ifact[i + 1] * (i + 1); ifact[0] = ifact[1]; } public ModInt this[int n, int r] { get { if (n < 0 || n >= fact.Length || r < 0 || r > n) return 0; return fact[n] * ifact[n - r] * ifact[r]; } } public ModInt RepeatedCombination(int n, int k) { if (k == 0) return 1; return this[n + k - 1, k]; } } #endregion } namespace CompLib.Util { using System; using System.Linq; class Scanner { private string[] _line; private int _index; private const char Separator = ' '; public Scanner() { _line = new string[0]; _index = 0; } public string Next() { if (_index >= _line.Length) { string s; do { s = Console.ReadLine(); } while (s.Length == 0); _line = s.Split(Separator); _index = 0; } return _line[_index++]; } public string ReadLine() { _index = _line.Length; return Console.ReadLine(); } public int NextInt() => int.Parse(Next()); public int NextInt1() => NextInt() - 1; public long NextLong() => long.Parse(Next()); public double NextDouble() => double.Parse(Next()); public decimal NextDecimal() => decimal.Parse(Next()); public char NextChar() => Next()[0]; public char[] NextCharArray() => Next().ToCharArray(); public string[] Array() { string s = Console.ReadLine(); _line = s.Length == 0 ? new string[0] : s.Split(Separator); _index = _line.Length; return _line; } public int[] IntArray() => Array().Select(int.Parse).ToArray(); public int[] IntArray1() => Array().Select(s => int.Parse(s) - 1).ToArray(); public long[] LongArray() => Array().Select(long.Parse).ToArray(); public double[] DoubleArray() => Array().Select(double.Parse).ToArray(); public decimal[] DecimalArray() => Array().Select(decimal.Parse).ToArray(); } }