#include <iostream>
#include <cstdio>
#include <map>

#define NMAX 400005

using namespace std;

long long a[NMAX] , b[NMAX];
long long n , x , sol;

map <long long , long long> mp;

int main() {
    #ifndef ONLINE_JUDGE
        freopen("input.txt" , "r" , stdin);
    #endif // ONLINE_JUDGE

    cin >> n;
    for(int i = 1 ; i <= n ; ++i) {
        cin >> x;
        a[i] = a[i - 1] + x;
    }

    for(long long i = 1 ; i <= n ; ++i) {
        cin >> x;
        b[i] = b[i - 1] + x;
    }

    for(long long i = 1 ; i <= n ; ++i) {
        long long dif = a[i] - b[i];
        if(dif == 0) {
            sol = max(sol , i);
        }

        else {
            if(mp[dif] == 0) {
                mp[dif] = i;
            }

            else {
                long long qq = mp[dif];
                sol = max(sol , i - mp[dif]);
            }
        }
    }

    cout << sol;
    return 0;
}