#include <bits/stdc++.h>
using namespace std;
const int N = 205;
int n;
int a[3][N], dp[3][N];
int main() {
  scanf("%d", &n);
  for (int i = 1; i <= 2; ++i) {
    for (int j = 1; j <= n; ++j) scanf("%d", &a[i][j]);
  }
  for (int i = 1; i <= 2; ++i) {
    for (int j = 1; j <= n; ++j) {
      dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]) + a[i][j];
    }
  }
  printf("%d\n", dp[2][n]);
  return 0;
}
