#include <bits/stdc++.h>
#define nmax 100010
#define ll long long
const int oo=1e9+7;
using namespace std;
int n,h[nmax],rmq[nmax][25];
ll f[nmax],g[nmax],w[nmax];
ll range(int l,int r)
{
if (l==0) return w[r];
return w[r]-w[l-1];
}
ll get(int x,int y)
{
int z=log2(y-x+1);
return min(rmq[x][z],rmq[y-(1<<z)+1][z]);
}
int rangemod(int l,int r)
{
if (l==0) return w[r]%oo;
return (w[r]-w[l-1])%oo;
}
ll cal(ll x,ll y)
{
if (x>y) return 0;
ll z=x+y; ll t=y-x+1;
if (z%2==0) z/=2; else t/=2;
z%=oo; t%=oo;
return z*t%oo;
}
int main()
{
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin>>n;
for (int i=1;i<=n;++i)
{
cin>>h[i];
rmq[i][0]=h[i];
}
for (int i=1;i<=n;++i)
{
cin>>w[i];
w[i]+=w[i-1];
}
for (int j=1;j<20;++j)
for (int i=0;i<=n-(1<<j)+1;++i)
rmq[i][j]=min(rmq[i][j-1],rmq[i+(1<<(j-1))][j-1]);
for (int i=1;i<=n;++i)
{
int l=0; int r=i-1;
while (l<r)
{
int mid=(l+r+1)>>1;
if (get(mid,i)<h[i]) l=mid;
else r=mid-1;
}
f[i] = f[i] + cal(1,h[i]) * cal(range(l+1,i-1)+1,range(l+1,i)) %oo; if (f[i]>=oo) f[i]-=oo;
f[i] = f[i] + g[l] * rangemod(i,i) %oo; if (f[i]>=oo) f[i]-=oo;
g[i] = g[i] + cal(1,h[i]) * rangemod(l+1,i) %oo; if (g[i]>=oo) g[i]-=oo;
g[i] = g[i] + g[l]; if (g[i]>=oo) g[i]-=oo;
}
int res=0;
for (int i=1;i<=n;++i)
{
res+=f[i];
if (res>=oo) res-=oo;
}
cout<<res;
return 0;
}
