package main

import (
	"fmt"
	"bufio"
	"os"
	"math"
)

func Max(a, b int) int {
	if a > b {
		return a
	} else {
		return b
	}
}

func Add(a, b int) int {
	if a == math.MinInt64 {
		return a
	} else {
		return a + b
	}
}

func main() {
	r := bufio.NewReader(os.Stdin)
	w := bufio.NewWriter(os.Stdout)
	defer w.Flush()
	var n, m int
	fmt.Fscan(r, &n, &m)
	a := make([]int, n)
	for i := 0; i < n; i++ {
		sum := 0
		for j := 0; j < m; j++ {
			var x int
			fmt.Fscan(r, &x)
			sum += x
		}
		a[i] = sum
	}
	dp := make([][]int, n+1)
	for i := 0; i <= n; i++ {
		dp[i] = make([]int, n+1)
		for j := 0; j <= n; j++ {
			dp[i][j] = math.MinInt64
		}
	}
	dp[0][0] = 0
	for i := 1; i <= n; i++ {
		dp[i][0] = 0
		for j := 1; j <= n; j++ {
			if j % 2 == 1 {
				dp[i][j] = Max(dp[i-1][j], Add(dp[i-1][j-1], a[i-1]))
			} else {
				dp[i][j] = Max(dp[i-1][j], Add(dp[i-1][j-1], -a[i-1]))
			}
		}
	}
	max := math.MinInt64
	for i := 0; i <= n; i++ {
		max = Max(max, dp[n][i])
	}
	fmt.Fprintln(w, max)
}