#include <iostream>
#include <iomanip>
using namespace std;

int main()
{
   int n, m,times=0;
   double max, min;
   cin >> n >> m;
   double a[100][20];
   double* p = new double[n];
   double(*q) = new double[n];
   for (int i = 0; i < n; i++)
   	for (int j = 0; j < m; j++)
   		cin >> a[i][j];
   for (int i = 0; i < n; i++)
   {
   	max = min = a[i][0];
   	for (int j = 0; j < m; j++)
   	{
   		if (a[i][j] > max)max = a[i][j];
   		if (a[i][j] < min)min = a[i][j];
   	}
   	*(p + times) = max+min;
   	times++;
   	 
   }
   for (int i = 0; i < n; i++)
   {
   	double add=0;
   	for (int j = 0; j < m; j++)
   	{
   		add += a[i][j];
   	}
   	add -= *(p + i);
   	*(q + i) = add / (m-2.0);
   }
   max = 0;
   for (int i = 0; i < n; i++)
   {
   	if (*(q + i) > max)max = *q + i;
   }
   cout << fixed << setprecision(2) << max;
   return 0;
} ```