#include <bits/stdc++.h>
using namespace std;
#define ll long long
const int mod = 1e9+7;
int n;
stack<int>st;
int h[100002], w[100002], dp[100002];
int sum[100002];
int logpow(int a, int b) {
int ans = 1, d = a;
while (b) {
if (b & 1)
ans = 1LL * ans * d % mod;
b >>= 1;
d = 1LL * d * d % mod;
}
return ans;
}
int calc (int w, int h) {
ll a1 = 1ll * w * (w + 1) / 2 % mod;
ll a2 = 1ll * h * (h + 1) / 2 % mod;
return 1ll * a1 * a2 % mod;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n;
for (int i = 1; i <= n; i++)
cin >> h[i];
for (int i = 1; i <= n; i++)
cin >> w[i];
st.push(0);
int ans = 0;
for (int i = 1; i <= n; i++) {
while (h[st.top()] >= h[i]) {
st.pop();
}
sum[i] = sum[i - 1] + w[i];
if (sum[i] >= mod)
sum[i] -= mod;
int x = st.top();
st.push(i);
if (x) {
int val = dp[x] - calc(w[x], h[x]);
if (val < 0)
val += mod;
val = 1ll * val * logpow(w[x], mod - 2) % mod;
dp[i] = 1ll * val * w[i] % mod;
int a1 = 1ll * h[x] * (h[x] + 1) / 2 % mod;
dp[i] = dp[i] + 1ll * w[x] * w[i] % mod * a1 % mod;
if (dp[i] >= mod)
dp[i] -= mod;
}
int a1 = 1ll * h[i] * (h[i] + 1) / 2 % mod;
dp[i] = dp[i] + 1ll * w[i] * (sum[i - 1] - sum[x] + mod) % mod * a1 % mod;
if (dp[i] >= mod)
dp[i] -= mod;
dp[i] = dp[i] + calc(w[i], h[i]);
if (dp[i] >= mod)
dp[i] -= mod;
ans = (ans + dp[i]);
if (ans >= mod)
ans -= mod;
}
cout << ans;
return 0;
}
