#include <bits/stdc++.h>
using namespace std;
#define ll long long
#define mod (ll)1000000007
ll m(ll a, ll b){
a %= mod; b %= mod;
return (a*b)%mod;
}
ll m(ll a, ll b, ll c){
a %= mod; b %= mod; c %= mod;
return m(m(a, b), c);
}
ll sum(ll x){
return ((x*(x+1))/2)%mod;
}
int main(){
ll n, ans; cin >> n;
ll h[n+1], w[n+1], p[n+1], dp[n+1];
h[0] = 0; p[0] = 0; dp[0] = 0, ans = 0;
for (int i = 1; i <= n; i++) cin >> h[i];
for (int i = 1; i <= n; i++) cin >> w[i];
for (int i = 1; i <= n; i++) p[i] = p[i-1]+w[i];
stack<ll> stk; stk.push(0);
for (int i = 1; i <= n; i++){
while (!stk.empty() and h[stk.top()] >= h[i]) stk.pop();
dp[i] = dp[stk.top()] + m(sum(h[i]), (p[i]-p[stk.top()]));
ans += m(dp[stk.top()], w[i]) + m(sum(h[i]), (p[i-1]-p[stk.top()]), w[i]) + m(sum(h[i]), sum(w[i]));
dp[i] %= mod; ans %= mod; stk.push(i);
}
cout<<ans;
}
