import sys
input = lambda :sys.stdin.readline()[:-1]
ni = lambda :int(input())
na = lambda :list(map(int,input().split()))
yes = lambda :print("yes");Yes = lambda :print("Yes");YES = lambda : print("YES")
no = lambda :print("no");No = lambda :print("No");NO = lambda : print("NO")
#######################################################################
def Primitive_Root(p):
    """Z/pZ上の原始根を見つける
 
    p:素数
    """
    if p==2:
        return 1
    if p==998244353:
        return 3
    if p==10**9+7:
        return 5
 
    fac=[]
    q=2
    v=p-1
 
    while v>=q*q:
        e=0
        while v%q==0:
            e+=1
            v//=q
 
        if e>0:
            fac.append(q)
        q+=1
 
    if v>1:
        fac.append(v)
 
    g=2
    while g<p:
        if pow(g,p-1,p)!=1:
            return None
 
        flag=True
        for q in fac:
            if pow(g,(p-1)//q,p)==1:
                flag=False
                break
 
        if flag:
            return g
 
        g+=1
 
#参考元 https://atcoder.jp/contests/practice2/submissions/16789717
def NTT(A):
    """AをMod を法とする数論変換を施す
 
    ※Modはグローバル変数から指定
    """
    primitive=Primitive_Root(Mod)
 
    N=len(A)
    H=(N-1).bit_length()
 
    if Mod==998_244_353:
        m=998_244_352
        u=119
        e=23
        S=[1,998244352,911660635,372528824,929031873,
           452798380,922799308,781712469,476477967,166035806,
           258648936,584193783,63912897,350007156,666702199,
           968855178,629671588,24514907,996173970,363395222,
           565042129,733596141,267099868,15311432]
    else:
        m=Mod-1
        e=((m&-m)-1).bit_length()
        u=m>>e
        S=[pow(primitive,(Mod-1)>>i,Mod) for i in range(e+1)]
 
    for l in range(H, 0, -1):
        d = 1 << l - 1
        U = [1]*(d+1)
        u = 1
        for i in range(d):
            u=u*S[l]%Mod
            U[i+1]=u
 
        for i in range(1 <<H - l):
            s=2*i*d
            for j in range(d):
                A[s],A[s+d]=(A[s]+A[s+d])%Mod, U[j]*(A[s]-A[s+d])%Mod
                s+=1
 
#参考元 https://atcoder.jp/contests/practice2/submissions/16789717
def Inverse_NTT(A):
    """AをMod を法とする逆数論変換を施す
 
    ※Modはグローバル変数から指定
    """
    primitive=Primitive_Root(Mod)
 
    N=len(A)
    H=(N-1).bit_length()
 
    if Mod==998244353:
        m=998_244_352
        e=23
        u=119
        S=[1,998244352,86583718,509520358,337190230,
           87557064,609441965,135236158,304459705,685443576,
           381598368,335559352,129292727,358024708,814576206,
           708402881,283043518,3707709,121392023,704923114,950391366,
           428961804,382752275,469870224]
    else:
        m=Mod-1
        e=(m&-m).bit_length()-1
        u=m>>e
 
        inv_primitive=pow(primitive,Mod-2,Mod)
        S=[pow(inv_primitive,(Mod-1)>>i,Mod) for i in range(e+1)]
 
    for l in range(1, H + 1):
        d = 1 << l - 1
        for i in range(1 << H - l):
            u = 1
            for j in range(i * 2 * d, (i * 2 + 1) * d):
                A[j+d] *= u
                A[j], A[j+d] = (A[j] + A[j+d]) % Mod, (A[j] - A[j+d]) % Mod
                u = u * S[l] % Mod
 
    N_inv=pow(N,Mod-2,Mod)
    for i in range(N):
        A[i]=A[i]*N_inv%Mod
 
#参考元 https://atcoder.jp/contests/practice2/submissions/16789717
def Convolution_Mod(A,B):
    """A,BをMod を法とする畳み込みを求める.
 
    ※Modはグローバル変数から指定
    """
    L=len(A)+len(B)-1
    H=L.bit_length()
    N=1<<H
 
    A=A+[0]*(N-len(A))
    B=B+[0]*(N-len(B))
 
    NTT(A)
    NTT(B)
 
    for i in range(N):
        A[i]=A[i]*B[i]%Mod
 
    Inverse_NTT(A)
 
    del A[L:]
    return A
#=================================================
Mod=998244353

mod = 998244353
nn = 10**6
fact = [1] * nn
for i in range(nn - 1):
    fact[i + 1] = fact[i] * (i + 1) % mod
invfact = [1] * nn
invfact[nn - 1] = pow(fact[nn - 1], mod - 2, mod)
for i in range(nn - 1)[::-1]:
    invfact[i] = invfact[i + 1] * (i + 1) % mod
 
def binom(x, y):
    if x < 0 or y < 0 or x - y < 0:
        return 0
    return fact[x] * invfact[y] % mod * invfact[x - y] % mod

n, m = na()

a = na()
b = na()
from collections import deque
dq = deque()


LA = [0] * m
LB = [0] * m
for i in range(m):
    A = []
    B = []
    la = float("inf")
    lb = float("inf")
    for j in range(i, n, m):
        la = min(la, a[j])
        lb = min(lb, b[j])
    LB[i] = lb
    LA[i] = la
S = sum(LB)
for i in range(m):
    la,lb = LA[i],LB[i]
    op = [1] * (la+lb+1)
    for j in range(i, n, m):
        for k in range(-lb, la+1):
            op[k+lb] *= binom(a[j]+b[j],k+b[j])
            op[k+lb] %= mod
    dq.append(op)

while len(dq)>1:
    l = dq.popleft()
    r = dq.popleft()
    z = Convolution_Mod(l, r)[:S+1]
    dq.append(z)
z = dq.popleft()
if len(z) <= S:
    print(0)
else:
    print(z[S])