#include <bits/stdc++.h>
using namespace std;
bool memory1;
typedef long long ll;
typedef unsigned long long ull;
typedef double dbe;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
typedef vector<ll> vll;
typedef vector<int> vii;
#define openFile(name) freopen((name ".inp"), "r", stdin), freopen((name ".out"), "w", stdout)
#define FOR(i, a, b, x) for (ll i = (a); i <= (b); i += (x))
#define ROF(i, a, b, x) for (ll i = (a); i >= (b); i += (x))
#define fi first
#define se second
#define MASK(x) (1LL << (x))
#define getBit(mask, i) (((mask) >> (i)) & 1LL)
#define BitOn(mask) (__builtin_popcountll(mask))
const int maxN = 1e5 + 5;
//const ll maxBit = MASK(8) + 2;
const ll LOG = 20;
const ll INF18 = 1e18;
const int INF9 = 1e9;
//const ll INF3f = 0x3f3f3f3f3f3f3f3f;
const ll MOD = 1e9 + 7;
//////////////////////////////////////////////
/////////////////nhan0123456//////////////////
//////////////////////////////////////////////
ll n;
pll a[maxN];
ll powMod(ll a, ll b, const ll c) {
ll ans = 1;
while (b > 0) {
if (b & 1) ans = ans * a % c;
a = a * a % c;
b = b >> 1;
}
return ans;
}
namespace sub4 {
bool check() {
FOR (i, 1, n, 1) if (a[i].fi != a[1].fi) return false;
return true;
}
ll Solve() {
ll sumW = 0;
FOR (i, 1, n, 1) (sumW += a[i].se) %= MOD;
/*
n * n - 1 / 2
1 1 1 1
2 2 2 2
9
h = 1
A = w * w - 1 / 2;
h = 2 ->
A2 = A + A * 2 = 3 * A
A3 = A2 + A * 3 = 6A
A4 = A3 + A * 4 = 10A = 6 + 4
A5 = A4 + A5 * 5 = 10 + 15
1 + 3 + 6 + 10 + 15 + ... + n
A = 1 + (1 + 2) + (1 + 2 + 3) + (1 + 2 + 3 + 4) + (1 + .. + n)
A = 1 + (1 + 2) + (1 + 2 + 3) + (1 + 2 + 3 + 4)
*/
ll t = (sumW + sumW * (sumW - 1) % MOD * powMod(2, MOD - 2, MOD) % MOD) % MOD;
// return (t * powMod(2, a[1].fi - 1, MOD) - 1 + MOD) % MOD;
ll ans = t;
FOR (i, 2, a[1].fi, 1) ans = (ans + t * i) % MOD;
return ans;
}
}
namespace sub3 {
bool check() {
FOR (i, 1, n, 1) if (a[i].fi > 2) return false;
return true;
}
ll Solve() {
ll ans = 0;
ll d = 0;
ll sumW = 0;
FOR (i, 1, n, 1) {
ans += sumW * a[i].se;
ans %= MOD;
ans += a[i].se + a[i].se * (a[i].se - 1) % MOD * powMod(2, MOD - 2, MOD) % MOD;
ans %= MOD;
if (a[i].fi == 2) {
d += a[i].se;
d %= MOD;
}
else {
ans += (d * 2 + d * (d - 1) % MOD) % MOD;
d = 0;
}
ans %= MOD;
(sumW += a[i].se) %= MOD;
}
ans += (d * 2 + d * (d - 1) % MOD) % MOD;
ans %= MOD;
return ans;
}
}
namespace sub2 {
ll s[55][55];
bool check() {
if (n > 50) return false;
FOR (i, 1, n, 1) {
if (a[i].fi > 50) return false;
if (a[i].se != 1) return false;
}
return true;
}
ll Solve() {
FOR (i, 1, n, 1) FOR (x, 1, a[i].fi, 1) s[i][x] = 1;
FOR (i, 1, 50, 1)
FOR (j, 1, 50, 1)
s[i][j] += s[i - 1][j] + s[i][j - 1] - s[i - 1][j - 1];
ll ans = 0;
FOR (x1, 1, 50, 1)
FOR (y1, 1, 50, 1)
FOR (x2, x1, 50, 1)
FOR (y2, y1, 50, 1) {
ll tt = (x2 - x1 + 1) * (y2 - y1 + 1);
if (s[x2][y2] - s[x1 - 1][y2] - s[x2][y1 - 1] + s[x1 - 1][y1 - 1] == tt)
++ans;
}
return ans;
}
}
void input() {
/*
dem so hcn
hi.. wi
*/
cin >> n;
FOR (i, 1, n, 1) cin >> a[i].fi;
FOR (i, 1, n, 1) cin >> a[i].se;
if (sub2::check()) cout << sub2::Solve();
else if (sub3::check()) cout << sub3::Solve();
// if (sub4::check()) cout << sub4::Solve();
}
int main() {
//openFile("temp");
ios_base::sync_with_stdio(0);
cin.tie(0);
input();
//bool memory2;
//cerr << "\n\n\nTime: "<< 1000.0 * clock() / CLOCKS_PER_SEC << " ms";
//cerr << "\n\n\nMemory: "<< abs(&memory1 - &memory2) * 1.0 / MASK(20) <<" MB";
return 0;
}
