#include <stdio.h>
#include <string.h>
#include <assert.h>

#include <set>
#include <vector>
#include <random>
#include <chrono>
#include <algorithm>

#define LOG(FMT...) fprintf(stderr, FMT)

#define eb emplace_back
#define em emplace

using namespace std;

typedef double DB;
typedef long long LL;
typedef long double LDB;
constexpr int N = 1024, M = 16, MS = 4096;
constexpr int mod = 998244353, G = 3;

constexpr int inv(int x, int k = mod - 2) {
	int r = 1;
	while (k) {
		if (k & 1) {
			r = x * (LL)r % mod;
		}
		x = x * (LL)x % mod;
		k >>= 1;
	}
	return r;
}

int last, lim, rt[N], rev[N];

void preNTT(int n) {
	lim = 1;
	while (lim < n) {
		lim <<= 1;
	}
	for (int i = 1; i < lim; ++i) {
		rev[i] = rev[i >> 1] >> 1 | (i & 1 ? lim >> 1 : 0);
	}
	for (int k = 2; k <= lim; k <<= 1) {
		rt[k / 2] = 1;
		LL v = inv(G, (mod - 1) / k);
		for (int j = k / 2 + 1; j < k; ++j) {
			rt[j] = rt[j - 1] * v % mod;
		}
	}
}

void NTT(int *f, bool ty = true) {
	if (!ty) {
		reverse(f + 1, f + lim);
	}
	for (int i = 0; i < lim; ++i) {
		if (i < rev[i]) {
			swap(f[i], f[rev[i]]);
		}
	}
	for (int k = 1; k < lim; k <<= 1) {
		for (int i = 0; i < lim; i += k << 1) {
			for (int j = i, *bf = rt + k, x; j < i + k; ++j, ++bf) {
				x = f[j | k] * (LL)*bf % mod;
				if ((f[j | k] = f[j] - x) < 0) {
					f[j | k] += mod;
				}
				if ((f[j] += x) >= mod) {
					f[j] -= mod;
				}
			}
		}
	}
	if (ty) {
		return;
	}
	LL v = mod - (mod - 1) / lim;
	for (int i = 0; i < lim; ++i) {
		f[i] = f[i] * v % mod;
	}
}

void Add(int &x, int y) {
	if ((x += y) >= mod) {
		x -= mod;
	}
}

void Fav(int &x, int y, int z) {
	x = (x + y * (LL)z) % mod;
}

int n, m;
int a[M], b[M];
int g[MS][N], f[MS][N], pro[M][N];

int fact[N], infact[N];

int C(int x, int y) {
	return x < y || y < 0 ? 0 : fact[x] * (LL)infact[y] % mod * infact[x - y] % mod;
}

int main() {
	scanf("%d%d", &n, &m);
	*fact = 1;
	for (int i = 1; i <= n; ++i) {
		fact[i] = fact[i - 1] * (LL)i % mod;
	}
	infact[n] = inv(fact[n]);
	for (int i = n; i; --i) {
		infact[i - 1] = infact[i] * (LL)i % mod;
	}
	for (int i = 0; i < m; ++i) {
		scanf("%d", a + i);
	}
	for (int i = 0; i < m; ++i) {
		scanf("%d", b + i);
	}
	preNTT(n);
	for (int i = 0; i < m; ++i) {
		int prod = 1;
		for (int j = 0; j < b[i]; ++j) {
			pro[i][j] = prod;
			g[1 << i][j] = infact[j] * (LL)prod % mod;
			prod = prod * (LL)(a[i] - j) % mod;
		}
		pro[i][b[i]] = prod;
		NTT(g[1 << i]);
	}
	// g[T][x]
	for (int s = 1; s < (1 << m); ++s) {
		for (int i = 0; i < m; ++i) {
			if (s >> i & 1) {
				continue;
			}
			for (int j = 0; j < lim; ++j) {
				g[s | 1 << i][j] = g[s][j] * (LL)g[1 << i][j] % mod;
			}
		}
	}
	g[0][0] = 1;
	for (int s = 1; s < (1 << m); ++s) {
		NTT(g[s], false);
		for (int j = 0; j < n; ++j) {
			g[s][j] = g[s][j] * (LL)fact[j] % mod;
		}
	}
	reverse(g, g + (1 << m));
	/* for (int s = 0; s < (1 << m); ++s) {
		for (int i = 0; i < n; ++i) {
			LOG("%d ", g[s][i]);
		}
		LOG("\n");
	} */
	int mask = 0;
	for (int i = 0; i < m; ++i) {
		if (b[i] == 0) {
			mask |= 1 << i;
		}
	}
	for (int s = (1 << m) - 2; ~s; --s) {
		if ((s & mask) != mask) {
			continue;
		}
		int Mx = 0;
		for (int i = 0; i < m; ++i) {
			if (!(s >> i & 1)) {
				Mx += b[i] - 1;
			}
		}
		int rest = n, need = n;
		for (int i = 0; i < m; ++i) {
			if (s >> i & 1) {
				rest -= b[i];
				need -= a[i];
			}
		}
		for (int x = Mx; ~x; --x) {
			int sump = 0;
			int env = inv(g[s][x]);
			for (int k = 0; k < m; ++k) {
				if ((s >> k & 1) || x < b[k] - 1) {
					continue;
				}
				if ((pro[k][b[k]] - pro[k][b[k] - 1] * (LL)(a[k] - b[k] + 1)) % mod) {
					LOG("??\n");
				}
				int p = g[s | 1 << k][x + 1 - b[k]] * (LL)env % mod * C(x, b[k] - 1) % mod * inv(need - x) % mod * pro[k][b[k]] % mod;
				Fav(f[s][x], f[s | 1 << k][x + 1 - b[k]], p);
				// LOG("p: %d\n", p);
				Add(sump, p);
			}
			Fav(f[s][x], f[s][x + 1], mod + 1 - sump);
			int w = (rest - x) * (LL)inv(need - x) % mod;
			Add(f[s][x], w);
			// LOG("f[%d][%d] = %d\n", s, x, f[s][x]);
		}
	}
	printf("%d\n", f[mask][0]);
	return 0;
}