#include<bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define ins insert
#define pq priority_queue
#define minele min_element
#define maxele max_element
#define lb lower_bound //first pos >= val
#define ub upper_bound // first pos > val
#define cnt_bit __builtin_popcount
#define debug(...) " [" << #__VA_ARGS__ ": " << (__VA_ARGS__) << "] "
//#pragma GCC optimize("Ofast")
//#pragma GCC target("avx,avx2,fma")
using namespace std;

mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;


int d4x[4] = {1, 0, -1, 0}; int d4y[4] = {0, 1, 0, -1};
int d8x[8] = {0, 1, 1, 1, 0, -1, -1, -1};
int d8y[8] = {1, 1, 0, -1, -1, -1, 0, 1};

const ll oo = 1e18;
const ll maxN = 3e5 + 100;

/* Author : Le Ngoc Bao Anh, 10A5, LQD High School for Gifted Student */

void maximize(ll &a, ll b) {
    if(a < b) a = b;
}

void minimize(ll &a, ll b) {
    if(a > b) a = b;
}

ll Node[maxN * 4], Lazy[maxN * 4], dp[maxN];
int L[maxN], R[maxN], L2[maxN], R2[maxN];
ll a[maxN], b[maxN];
ll rmq[maxN][18];

void Down(int id) {
    ll x = Lazy[id]; Lazy[id] = -oo;
    maximize(Node[id * 2], x); maximize(Node[id * 2 + 1], x);
    maximize(Lazy[id * 2], x); maximize(Lazy[id * 2 + 1], x);
}

void Update(int L, int R, int lo, int hi, int id, ll x) {
    if(L > hi || R < lo) return;
    if(lo <= L && R <= hi) {
        maximize(Node[id], x);
        maximize(Lazy[id], x);
        return;
    }

    Down(id);
    int mid = (L + R) >> 1;
    Update(L, mid, lo, hi, id * 2, x);
    Update(mid + 1, R, lo, hi, id * 2 + 1, x);
    Node[id] = max(Node[id * 2], Node[id * 2 + 1]);
}

ll Get(int L, int R, int lo, int hi, int id) {
    if(L > hi || R < lo) return -oo;
    if(lo <= L && R <= hi) return Node[id];

    Down(id);
    int mid = (L + R) >> 1;
    return max(Get(L, mid, lo, hi, id * 2), Get(mid + 1, R, lo, hi, id * 2 + 1));
}

void solve() {
    int n; cin >> n;
    for(int i = 1; i <= n; i++) cin >> a[i];
    for(int i = 1; i <= n; i++) cin >> b[i];

    int g = 17;
    for(int i = 1; i <= n; i++) rmq[i][0] = b[i];
    for(int j = 1; j <= g; j++) {
        for(int i = 1; i <= n; i++) {
            if(i + (1 << j) - 1 > n) break;
            rmq[i][j] = max(rmq[i][j - 1], rmq[i + (1 << (j - 1))][j - 1]);
        }
    }

    stack<int> q;

    //cal L
    for(int i = 1; i <= n; i++) {
        while(!q.empty()) {
            if(b[q.top()] < b[i]) q.pop();
            else break;
        }

        if(!q.empty()) L[i] = q.top();
        q.push(i);
    }

    //cal R
    while(!q.empty()) q.pop();
    for(int i = n; i >= 1; i--) {
        while(!q.empty()) {
            if(b[q.top()] < b[i]) q.pop();
            else break;
        }

        if(!q.empty()) R[i] = q.top();
        else R[i] = n + 1;
        q.push(i);
    }

    auto get_max = [&](int L, int R) -> int {
        int len = (R - L + 1);
        int x = log2(len);
        return max(rmq[L][x], rmq[R - (1 << x) + 1][x]);
    };

    //Cal L2
    for(int i = 1; i <= n; i++) {
        if(!L[i]) continue;
        int lo = 1, hi = L[i] - 1;
        while(lo <= hi) {
            int mid = (lo + hi) >> 1;
            if(get_max(mid, L[i] - 1) > b[i]) {
                L2[i] = mid;
                lo = mid + 1;
            } else {
                hi = mid - 1;
            }
        }
    }

    //cal R2
    for(int i = 1; i <= n; i++) {
        if(R[i] > n) {
            R2[i] = n + 1;
            continue;
        }
        R2[i] = n + 1;
        int lo = R[i] + 1, hi = n;
        while(lo <= hi) {
            int mid = (lo + hi) >> 1;
            if(get_max(R[i] + 1, mid) > b[i]) {
                R2[i] = mid;
                hi = mid - 1;
            } else {
                lo = mid + 1;
            }
        }
    }

    for(int i = 1; i <= n; i++) dp[i] = -oo;
    for(int i = 1; i <= 4 * (n + 1); i++) Node[i] = Lazy[i] = -oo;
    Update(0, n, 0, 0, 1, 0);

    for(int i = 1; i <= n; i++) {
        dp[i] = Get(0, n, i, i, 1);
        ll g = -oo;
        if(L[i]) {
            g = Get(0, n, L2[i], L[i] - 1, 1);
            dp[i] = max(dp[i], g + a[i]);
        }

        ll x = Get(0, n, L[i], i - 1, 1);
        if(R[i] <= n) {
            Update(0, n, R[i], R2[i] - 1, 1, x + a[i]);
        }
        if(i <= R[i] - 2) Update(0, n, i + 1, R[i] - 1, 1, g + a[i]);
        Update(0, n, i, i, 1, dp[i]);
    }

    cout << dp[n];
}

int main()
{
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    // #ifndef ONLINE_JUDGE
    // freopen("input.txt", "r", stdin);
    // freopen("output.txt", "w", stdout);
    // #else
    // //online
    // #endif

    int tc = 1, ddd = 0;
    // cin >> tc;
    while(tc--) {
        //ddd++;
        //cout << "Case #" << ddd << ": ";
        solve();
    }
}