import java.util.*;
import java.lang.*;
import java.io.*;
 
class Main
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		double x, max = 0.0;
		int m = in.nextInt(), n = in.nextInt();
		for (int i = 0; i < m; i++) {
			double s = 0.0;
			for (int j = 0; j < n; j++) {
				x = in.nextDouble();
				s += Math.abs(x);
			}
			if (s > max)
				max = s;
		}
		System.out.println(max);
	}
}

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NCA1CjEgLTMgMiA0IDAKLTMgLTcuNSAyLjMgLTMuMSAyLjgKMy40IC00LjUgMCAwIDIKMy4yIDQuNyAyLjggLTMuMSAtNC4z

4 5
1 -3 2 4 0
-3 -7.5 2.3 -3.1 2.8
3.4 -4.5 0 0 2
3.2 4.7 2.8 -3.1 -4.3