#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
const int MAXN = 1e5;
const ll INF = 1e18;
const ll MOD = 1e9+7;
int N;
ll W[MAXN+10], H[MAXN+10];
pll tree[MAXN*4+10];
void init(int node, int tl, int tr)
{
if(tl==tr)
{
tree[node]={H[tl], tl};
return;
}
int mid=tl+tr>>1;
init(node*2, tl, mid);
init(node*2+1, mid+1, tr);
tree[node]=min(tree[node*2], tree[node*2+1]);
}
pll query(int node, int tl, int tr, int l, int r)
{
if(l<=tl && tr<=r) return tree[node];
if(r<tl || tr<l) return {INF, -1};
int mid=tl+tr>>1;
return min(query(node*2, tl, mid, l, r), query(node*2+1, mid+1, tr, l, r));
}
ll ans=0;
ll f(ll x)
{
x%=MOD;
return x*(x+1)%MOD*((MOD+1)/2)%MOD;
}
ll f(ll l, ll r)
{
return ((f(r)-f(l))%MOD+MOD)%MOD;
}
void solve(int l, int r, ll h)
{
if(l>r) return;
pll p=query(1, 1, N, l, r);
ans+=f(h, p.first)*f(0, W[r]-W[l-1])%MOD;
ans%=MOD;
solve(l, p.second-1, p.first);
solve(p.second+1, r, p.first);
}
int main()
{
scanf("%d", &N);
for(int i=1; i<=N; i++) scanf("%lld", &H[i]);
for(int i=1; i<=N; i++) scanf("%lld", &W[i]), W[i]+=W[i-1];
init(1, 1, N);
solve(1, N, 0);
printf("%lld\n", ans);
}
