/** work as hard as you can and keep the first place **/
#pragma GCC optimize("Ofast")
#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef pair < int, int > pii;
typedef pair < ll, ll > pll;
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define SZ(x) (int)x.size()
#define Mp make_pair
const int N = 1e6 + 10;
const ll mod = 1e9 + 7;
const ll inf = 8e18;
const int LOG = 20;
ll pw(ll a, ll b, ll M = mod, ll ret = 1) { while(b) { ret = ret * (b & 1? a : 1) % M, a = a * a % M, b >>= 1; } return ret; }
ll inv2, ps[N];
int n, h[N], w[N];
vector < int > cm, Q[N];
set < pair < pii, ll > > st;
ll C2(ll x)
{
x %= mod;
return x * (x - 1) % mod * inv2 % mod;
}
ll baze(int l, int r)
{
return 1ll * (r + l) * (r - l + 1) % mod * inv2 % mod;
}
void add(int l, int r)
{
if(l > r) return;
st.insert(Mp(Mp(l, r), ps[r] - ps[l - 1]));
}
int main()
{
inv2 = pw(2, mod - 2, mod);
scanf("%d", &n);
for(int i = 1; i <= n; i ++)
{
scanf("%d", &h[i]);
cm.push_back(h[i]);
}
for(int i = 1; i <= n; i ++)
{
scanf("%d", &w[i]);
ps[i] = ps[i - 1] + w[i];
}
st.insert(Mp(Mp(1, n), ps[n]));
cm.push_back(0);
sort(all(cm));
cm.resize(unique(all(cm)) - cm.begin());
for(int i = 1; i <= n; i ++)
{
int cu = lower_bound(all(cm), h[i]) - cm.begin();
Q[cu].push_back(i);
}
ll sum = C2(ps[n] + 1), tot = 0;
for(int i = 1; i < SZ(cm); i ++)
{
for(auto id : Q[i - 1])
{
auto it = st.lower_bound(Mp(Mp(id, 1e9), -1));
it --;
int l = (*it).F.F, r = (*it).F.S;
sum = (sum - C2(ps[r] - ps[l - 1] + 1) + mod) % mod;
st.erase(it);
add(l, id - 1), add(id + 1, r);
sum = (sum + C2(ps[r] - ps[id] + 1) + C2(ps[id - 1] - ps[l - 1] + 1)) % mod;
}
///printf("i = %d cm = %d sum = %lld\n", i, cm[i], sum);
tot = (tot + baze(cm[i - 1] + 1, cm[i]) * sum % mod) % mod;
}
printf("%lld", tot);
return 0;
}
/** test corner cases(n = 1?) watch for overflow or minus indices **/
