def main():
import sys
def get_ints(): return list(map(int, sys.stdin.readline().strip().split()))
[n]=get_ints()
g=[0]+get_ints()
d=[0]+get_ints()
zlicz=[[0 for _ in range(n+2)]for _ in range(3)]
zlicz[1][1]=g[1]
zlicz[2][1]=d[1]
zlicz[0][2]=max(g[1],d[1])
for i in range(2,n+1):
zlicz[1][i]=g[i]+max(zlicz[2][i-1],zlicz[0][i-1])
zlicz[2][i]=d[i]+max(zlicz[1][i-1],zlicz[0][i-1])
zlicz[0][i]=max(zlicz[1][i-1],zlicz[2][i-1])
print(max(zlicz[0][-2],zlicz[1][-2],zlicz[2][-2]))
main()#include <bits/stdc++.h>
#define int long long
#define pii pair <int,int>
#define st first
#define nd second
#define vi vector <int>
#define vpii vector <pii>
#define pb push_back
#define pf push_front
#define FOR(a, b, c) for (int i = a; i <= b; i += c)
#define ROS(a, b, c) for (int i = a; i >= b; i -= c)
#define lb lower_bound
#define ub upper_bound
#define FILE ""
#define trii pair <int, pii>
using namespace std;
const int oo = 1e18;
const int N = 3e5 + 1;
const int mod = 1e9 + 7;
const int blocks = 448;
int n, a[N], b[N];
int dp[N][3];
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);cout.tie(0);
//freopen(FILE".inp","r", stdin);
//freopen(FILE".out","w", stdout);
cin >> n;
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
for (int i = 1; i <= n; i++)
cin >> b[i];
dp[0][0] = 0;
dp[0][1] = 0;
dp[0][2] = 0;
for (int i = 1; i <= n; i++)
{
dp[i][0] = max(dp[i - 1][0], max(dp[i - 1][1], dp[i - 1][2]));
dp[i][1] = max(dp[i - 1][0] + a[i], dp[i - 1][2] + a[i]);
dp[i][2] = max(dp[i - 1][0] + b[i], dp[i - 1][1] + b[i]);
}
cout << max(dp[n][0], max(dp[n][1], dp[n][2]));
return 0;
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