use proconio::input;

fn main() {
    input! {
        n: usize,
        a: [[i64; n]; 3],
    }

    let mut dp = [[-1; 2]; 5];
    dp[0] = [0; 2];

    for i in 0..n {
        let mut ndp = [[-1; 2]; 5];
        for j in 0..5 {
            for k in 0..2 {
                if dp[j][k] == -1 {
                    continue;
                }
                for nj in j..5 {
                    // 01010 or 01210
                    let target = nj & 1 + if nj == 2 { 2 * k } else { 0 };
                    ndp[nj][k] = ndp[nj][k].max(dp[j][k] + a[target][i]);
                }
            }
        }
        dp = ndp;
    }

    let ans = dp.iter().flatten().max().unwrap();
    println!("{ans}");
}