//---------- begin SegmentTree Point update Range query ----------
mod segment_tree {
    pub struct PURQ<T: Clone, F: Fn(T, T) -> T> {
        n: usize,
        a: Vec<T>,
        id: T,
        op: F,
    }
    #[allow(dead_code)]
    impl<T: Clone, F: Fn(T, T) -> T> PURQ<T, F> {
        pub fn new(n: usize, id: T, op: F) -> PURQ<T, F> {
            let mut k = 1;
            while k < n {
                k *= 2;
            }
            PURQ {
                n: k,
                a: vec![id.clone(); 2 * k],
                id: id,
                op: op,
            }
        }
        pub fn update(&mut self, x: usize, v: T) {
            let mut k = self.n + x;
            let a = &mut self.a;
            a[k] = v;
            k >>= 1;
            while k > 0 {
                a[k] = (self.op)(a[2 * k].clone(), a[2 * k + 1].clone());
                k >>= 1;
            }
        }
        pub fn update_tmp(&mut self, x: usize, v: T) {
            self.a[x + self.n] = v;
        }
        pub fn update_all(&mut self) {
            for k in (1..(self.n)).rev() {
                self.a[k] = (self.op)(self.a[2 * k].clone(), self.a[2 * k + 1].clone());
            }
        }
        pub fn find(&self, mut l: usize, mut r: usize) -> T {
            let mut p = self.id.clone();
            let mut q = self.id.clone();
            l += self.n;
            r += self.n;
            while l < r {
                if (l & 1) == 1 {
                    p = (self.op)(p, self.a[l].clone());
                    l += 1;
                }
                if (r & 1) == 1 {
                    r -= 1;
                    q = (self.op)(self.a[r].clone(), q);
                }
                l >>= 1;
                r >>= 1;
            }
            (self.op)(p, q)
        }
    }
}
//---------- end SegmentTree Point update Range query ----------
//https://qiita.com/tanakh/items/0ba42c7ca36cd29d0ac8
macro_rules! input {
    (source = $s:expr, $($r:tt)*) => {
        let mut iter = $s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
    ($($r:tt)*) => {
        let s = {
            use std::io::Read;
            let mut s = String::new();
            std::io::stdin().read_to_string(&mut s).unwrap();
            s
        };
        let mut iter = s.split_whitespace();
        input_inner!{iter, $($r)*}
    };
}

macro_rules! input_inner {
    ($iter:expr) => {};
    ($iter:expr, ) => {};
    ($iter:expr, $var:ident : $t:tt $($r:tt)*) => {
        let $var = read_value!($iter, $t);
        input_inner!{$iter $($r)*}
    };
}

macro_rules! read_value {
    ($iter:expr, ( $($t:tt),* )) => {
        ( $(read_value!($iter, $t)),* )
    };
    ($iter:expr, [ $t:tt ; $len:expr ]) => {
        (0..$len).map(|_| read_value!($iter, $t)).collect::<Vec<_>>()
    };
    ($iter:expr, chars) => {
        read_value!($iter, String).chars().collect::<Vec<char>>()
    };
    ($iter:expr, usize1) => {
        read_value!($iter, usize) - 1
    };
    ($iter:expr, $t:ty) => {
        $iter.next().unwrap().parse::<$t>().expect("Parse error")
    };
}

//

fn run() {
    input! {
        n: usize,
        m: usize,
        a: [i64; n - 1],
        b: [[i64; m]; n],
    }
    let mut dp = vec![vec![0; n + 1]; n + 1];
    for i in 0..m {
        let mut s = segment_tree::PURQ::new(n, (0, 0), std::cmp::max);
        for j in 0..n {
            s.update_tmp(j, (b[j][i], j));
        }
        s.update_all();
        let mut stack = vec![];
        stack.push((0, n - 1));
        while let Some((l, r)) = stack.pop() {
            let (v, k) = s.find(l, r + 1);
            dp[l][k] += v;
            dp[k + 1][k] -= v;
            dp[l][r + 1] -= v;
            dp[k + 1][r + 1] += v;
            if l < k {
                stack.push((l, k - 1));
            }
            if k < r {
                stack.push((k + 1, r));
            }
        }
    }
    for i in 0..n {
        for j in 1..n {
            dp[i][j] += dp[i][j - 1];
        }
    }
    for i in 1..n {
        for j in 0..n {
            dp[i][j] += dp[i - 1][j];
        }
    }
    let mut d = a.clone();
    d.push(0);
    for i in (0..(n - 1)).rev() {
        d[i] += d[i + 1];
    }
    let mut ans = 0;
    for l in 0..n {
        for r in l..n {
            let v = dp[l][r] - (d[l] - d[r]);
            ans = std::cmp::max(ans, v);
        }
    }
    println!("{}", ans);
}

fn main() {
    run();
}


Measured memory_bytes: 252152