import java.util.*;
import java.lang.*;
import java.io.*;

class Ideone
{
	public static void main (String[] args) throws java.lang.Exception
	{
		Scanner in = new Scanner(System.in);
		int m, n;
		m = in.nextInt();
		n = in.nextInt();
		double[] a = new double[m*n+1];
		double sum1 = 1, sum2 = 1, sum3 = 1;
		for (int i = 1; i <= m*n; i++)
		{
			a[i] = in.nextDouble();
			if (i <= m)
			{
				sum1 *= a[i];
			}
			if ((i > m) && (i <= 2*m))
			{
				sum2 *= a[i];
			}
			if ((i > (n - 1)*m) && (i <= n*m))
			{
				sum3 *= a[i];
			}
		}
		System.out.println(sum1 + sum2 + sum3); 
	}
}