#include<bits/stdc++.h>
#define pb push_back
using namespace std;
const int maxn = 1e5 + 10;
long long n, h[maxn], w[maxn];
long long pref[maxn];
int main()
{
cin >> n;
for (long long i = 1; i <= n; ++ i)
cin >> h[i];
for (long long i = 1; i <= n; ++ i)
{
cin >> w[i];
pref[i] += w[i];
}
w[n+1] = 0;
h[n+1] = 0;
vector < pair < long long /*visochina*/, long long/*long longerval*/ > > g;
g.pb(make_pair(0, 0));
long long ans = 0, mod = 1e9+7;
for (long long i = 1; i <= n + 1; ++ i)
{
long long sumaw = 0;
while(g.back().first > h[i])
{
sumaw += g.back().second;
sumaw %= mod;
long long currh = g.back().first;
long long currw = g.back().second;
// cout << currh << ", " << currw << endl;
long long sz = g.size();
long long pre = g[sz-2].first;
long long limit = max(pre, h[i]);
long long diffh = currh - limit;
//cout << sumaw << " " << diffh << endl;
ans += (((diffh) * (diffh+1)/2 + diffh * limit) % mod) * (((sumaw + 1) * (sumaw) / 2) % mod);
ans %= mod;
g.pop_back();
}
sumaw += w[i];
sumaw %= mod;
g.pb(make_pair(h[i], sumaw ));
}
cout << ans << endl;
return 0;
}
