#include <iostream>
#include <map>

using namespace std;


long n,i,j,st,mx,dr,sumA[100005],sumB[100005],A[100005],B[100005],dif[100005];
map <int,int> M;
int main()
{
    /*
6
4 1 2 3 4 5
2 5 4 3 2 1
    */
    cin>>n;

    for (i=1;i<=n;i++)
        cin>>A[i];
    for (i=1;i<=n;i++)
        cin>>B[i];

    for (i=1;i<=n;i++)
    {
        sumA[i]=sumA[i-1]+A[i];
        sumB[i]=sumB[i-1]+B[i];
        dif[i]=sumA[i]-sumB[i];
        if (!M[dif[i]])
            M[dif[i]] = i;
        if (sumA[i]==sumB[i])
            mx=i;
        if (M[-dif[i]])
        {
            if (i-M[-dif[i]]+1>mx)
                mx=i-M[-dif[i]]+1;
        }
    }
    cout<<mx<<'\n';


    return 0;
}