#面白すぎます！！！ # https://github.com/tatyam-prime/SortedSet/blob/main/SortedSet.py import math from bisect import bisect_left, bisect_right from typing import Generic, Iterable, Iterator, TypeVar T = TypeVar('T') class SortedSet(Generic[T]): BUCKET_RATIO = 16 SPLIT_RATIO = 24 def __init__(self, a: Iterable[T] = []) -> None: "Make a new SortedSet from iterable. / O(N) if sorted and unique / O(N log N)" a = list(a) n = len(a) if any(a[i] > a[i + 1] for i in range(n - 1)): a.sort() if any(a[i] >= a[i + 1] for i in range(n - 1)): a, b = [], a for x in b: if not a or a[-1] != x: a.append(x) n = self.size = len(a) num_bucket = int(math.ceil(math.sqrt(n / self.BUCKET_RATIO))) self.a = [a[n * i // num_bucket : n * (i + 1) // num_bucket] for i in range(num_bucket)] def __iter__(self) -> Iterator[T]: for i in self.a: for j in i: yield j def __reversed__(self) -> Iterator[T]: for i in reversed(self.a): for j in reversed(i): yield j def __eq__(self, other) -> bool: return list(self) == list(other) def __len__(self) -> int: return self.size def __repr__(self) -> str: return "SortedSet" + str(self.a) def __str__(self) -> str: s = str(list(self)) return "{" + s[1 : len(s) - 1] + "}" def _position(self, x: T) -> tuple[list[T], int, int]: "return the bucket, index of the bucket and position in which x should be. self must not be empty." for i, a in enumerate(self.a): if x <= a[-1]: break return (a, i, bisect_left(a, x)) def __contains__(self, x: T) -> bool: if self.size == 0: return False a, _, i = self._position(x) return i != len(a) and a[i] == x def add(self, x: T) -> bool: "Add an element and return True if added. / O(√N)" if self.size == 0: self.a = [[x]] self.size = 1 return True a, b, i = self._position(x) if i != len(a) and a[i] == x: return False a.insert(i, x) self.size += 1 if len(a) > len(self.a) * self.SPLIT_RATIO: mid = len(a) >> 1 self.a[b:b+1] = [a[:mid], a[mid:]] return True def _pop(self, a: list[T], b: int, i: int) -> T: ans = a.pop(i) self.size -= 1 if not a: del self.a[b] return ans def discard(self, x: T) -> bool: "Remove an element and return True if removed. / O(√N)" if self.size == 0: return False a, b, i = self._position(x) if i == len(a) or a[i] != x: return False self._pop(a, b, i) return True def lt(self, x: T) -> T | None: "Find the largest element < x, or None if it doesn't exist." for a in reversed(self.a): if a[0] < x: return a[bisect_left(a, x) - 1] def le(self, x: T) -> T | None: "Find the largest element <= x, or None if it doesn't exist." for a in reversed(self.a): if a[0] <= x: return a[bisect_right(a, x) - 1] def gt(self, x: T) -> T | None: "Find the smallest element > x, or None if it doesn't exist." for a in self.a: if a[-1] > x: return a[bisect_right(a, x)] def ge(self, x: T) -> T | None: "Find the smallest element >= x, or None if it doesn't exist." for a in self.a: if a[-1] >= x: return a[bisect_left(a, x)] def __getitem__(self, i: int) -> T: "Return the i-th element." if i < 0: for a in reversed(self.a): i += len(a) if i >= 0: return a[i] else: for a in self.a: if i < len(a): return a[i] i -= len(a) raise IndexError def pop(self, i: int = -1) -> T: "Pop and return the i-th element." if i < 0: for b, a in enumerate(reversed(self.a)): i += len(a) if i >= 0: return self._pop(a, ~b, i) else: for b, a in enumerate(self.a): if i < len(a): return self._pop(a, b, i) i -= len(a) raise IndexError def index(self, x: T) -> int: "Count the number of elements < x." ans = 0 for a in self.a: if a[-1] >= x: return ans + bisect_left(a, x) ans += len(a) return ans def index_right(self, x: T) -> int: "Count the number of elements <= x." ans = 0 for a in self.a: if a[-1] > x: return ans + bisect_right(a, x) ans += len(a) return ans mod = 998244353 comb_num = 2*10**6 + 20 F = [1] * comb_num F_ = [1] * comb_num for i in range(2, comb_num): F[i] = F[i-1]*i%mod F_[-1] = pow(F[-1], -1, mod) for i in range(comb_num-1, 0, -1): F_[i-1] = F_[i]*i%mod def comb(a, b): if 0 <= b <= a: return F[a] * F_[b] * F_[a-b] % mod else: return 0 def cal(t): t //= 2 return comb(2*t, t) - comb(2*t, t-1) def main(): n, q = list(map(int, input().split())) A = [0 if s == "Y" else 1 for s in input()] rep = 1 i = 0 sl = SortedSet([0, n]) c = 0 for i in range(1, n): if A[i-1] != A[i]: sl.add(i) for i in range(len(sl)-2): if (sl[i+1]-sl[i])%2: c += 1 else: t = sl[i+1]-sl[i] rep = rep * cal(t) % mod for _ in range(q): Q = list(map(int, input().split())) if Q[0] == 1: i = Q[1]-1 Y = [] Z = [] if i and A[i-1] != A[i]: Y.append(i) elif i: Z.append(i) if i < n-1 and A[i] != A[i+1]: Y.append(i+1) elif i < n-1: Z.append(i+1) A[i] ^= 1 for i in Y: idx = sl.index_right(i)-1 l, r = sl[idx-1], sl[idx+1] #print(l, i, r, "OK") if (i-l) % 2: c -= 1 else: rep = rep * pow(cal(i-l), -1, mod) % mod if r != n: if (r-i) % 2: c -= 1 else: rep = rep * pow(cal(r-i), -1, mod) % mod if r != n: if (r-l) % 2: c += 1 else: rep = rep * cal(r-l) % mod sl.pop(idx) for i in Z: idx = sl.index_right(i)-1 l, r = sl[idx], sl[idx+1] #print(l, i, r, "NG") if r != n: if (r-l) % 2: c -= 1 else: rep = rep * pow(cal(r-l), -1, mod) % mod if (i-l) % 2: c += 1 else: rep = rep * cal(i-l) % mod if r != n: if (r-i) % 2: c += 1 else: rep = rep * cal(r-i) % mod sl.add(i) else: k = Q[1] if c: print(0) else: l = sl[-2] m = l//2 a = k-m b = (n-k)-m if A[l]: if a < b: print(0) else: print(rep * (comb(a+b, a) - comb(a+b, b-1)) % mod) else: if b < a: print(0) else: print(rep * (comb(a+b, a) - comb(a+b, a-1)) % mod) main()