#include <bits/stdc++.h>
using namespace std;
long long h[100007];
long long w[100007];
long long wyndla(long long a, long long b)
{
__int128 aa = (__int128)a * ((__int128)a + (__int128)1) / (__int128)2;
__int128 bb = (__int128)b * ((__int128)b + (__int128)1) / (__int128)2;
aa %= (__int128)1000000007;
bb %= (__int128)1000000007;
return (((aa % (long long)1000000007) * (bb % (long long)1000000007)) % (long long)1000000007);
}
int main()
{
long long n, wyn = 0;
cin >> n;
deque<pair<long long, long long>> q; // wys, szer
for (long long i = 0; i < n; i++)
{
cin >> h[i];
}
for (long long i = 0; i < n; i++)
{
cin >> w[i];
}
for (long long i = 0; i <= n; i++)
{
if (q.empty())
{
q.push_back({h[i], w[i]});
}
else
{
long long ilesze = 0;
while (!q.empty() && (q.back()).first > h[i])
{
auto x = q.back();
ilesze += x.second;
q.pop_back();
long long wys = 0;
if(!q.empty())
{
wys = (q.back()).first;;
}
//cout << x.second << " " << x.first << " " << wys << endl;
wyn += wyndla(ilesze, x.first);
wyn -= wyndla(ilesze, wys);
wyn += 1000000007;
wyn %= 1000000007;
}
if (q.empty() || (q.back()).first < h[i])
{
q.push_back({h[i], w[i] + ilesze});
}
else
{
auto x = q.back();
q.pop_back();
x.second += w[i] + ilesze;
q.push_back(x);
}
}
}
cout << wyn << endl;
return 0;
}
