#include <bits/stdc++.h>
using namespace std;
const long long mod = 1000000007;
const int maxn = 105;
long long dp[maxn][maxn * 10], fac[maxn * 10], invfac[maxn * 10];
int x[maxn], y[maxn], sum[maxn * 10];
long long qp(long long x, long long p, long long MOD) {
  long long res = 1;
  while (p) {
    if (p & 1) res = res * x % MOD;
    x = x * x % MOD;
    p >>= 1;
  }
  return res;
}
long long C(int n, int k) {
  if (k > n) return 0;
  return fac[n] * invfac[k] % mod * invfac[n - k] % mod;
}
int main() {
  fac[0] = 1;
  invfac[0] = 1;
  for (int i = 1; i < maxn * 10; i++) fac[i] = fac[i - 1] * 1ll * i % mod;
  invfac[maxn * 10 - 1] = qp(fac[maxn * 10 - 1], mod - 2, mod);
  for (int i = maxn * 10 - 2; i >= 1; i--)
    invfac[i] = invfac[i + 1] * 1ll * (i + 1) % mod;
  int m, n = 0;
  scanf("%d", &m);
  for (int i = 1; i <= m; i++) scanf("%d", &x[i]), sum[i] = sum[i - 1] + x[i];
  for (int i = 1; i <= m; i++) scanf("%d", &y[i]);
  dp[0][0] = 1;
  for (int i = 1; i <= m; i++) {
    for (int j = 0; j <= sum[i]; j++) {
      for (int k = 0; k <= min(y[i], j); k++) {
        if (j - k >= 0 && sum[i] - (j - k) >= 0) {
          dp[i][j] =
              (dp[i][j] + dp[i - 1][j - k] * C(sum[i] - (j - k), k) % mod) %
              mod;
        }
      }
    }
  }
  long long ans = dp[m][sum[m]];
  for (int i = 1; i <= m; i++) {
    ans = ans * C(sum[m] - sum[i - 1], x[i]) % mod;
  }
  printf("%lld\n", ans);
  return 0;
}
