#include<stdio.h>
void order(int a[100][20],int n,int m)
{
	int i, j, k;
	for (i = 0; i < n; i++) {
		for (int q = 0; q < m - 2;q++) {
			for (j = 0; j < m - 1; j++) {
				if (a[i][j] > a[i][j + 1]) {
					k = a[i][j];
					a[i][j] = a[i][j + 1];
					a[i][j + 1] = k;
				}
			}

		}
	}
}
void average(int a[100][20],int n,int m,double k[100])
{
	int i, j,h;
	for (i = 0; i < n; i++) {
		h = 0;
		for (j = 1; j < m - 1; j++) {
			h += a[i][j];
		}
		k[i] = h / (m-2.0);
	}
}
void order2(double k[100],int n)
{
	int j, p;
	for (int q = 0; q < n - 2; q++) {
		for (j = 0; j < n - 1; j++) {
			if (k[j] > k[j + 1]) {
				p = k[j];
				k[j] = k[j + 1];
				k[j + 1] = p;
			}
		}

	}
}
int main()
{
	int n, m, a[100][20];
	double k[100] = {0};
	scanf("%d %d", &n, &m);
	for (int i = 0; i < n; i++) {
		for (int j = 0; j < m; j++) {
			scanf("%d", &a[i][j]);
		}
	}
	order(a, n, m);
	average(a, n, m, k);
	order2(k, n);
	printf("%.2lf", k[n-1]);
	return 0;
}

出啥问题了？/_ \