#include <stdio.h>
int main(){
    int m,n;
    scanf("%d %d", &m, &n);
    if (m <= 0 || n <= 0){
        printf("Invaild Input");
        return 0;
    }
    float arr[100], temp;
    for(int i = 0; i < m; i++) {
        float x;
         for(int j = 0; j < n; j++) {
             float temp;
             scanf ("%f", &temp);
             if(j == 0) x = temp;
        }
        arr[i] = x;
        }
        for (int i = 0; i < m - 1; i++) {
                 for(int j = i + 1; j < m ; j++) {
                     if(arr[i] > arr[j]){
                          float t = arr[i];
                          arr[i] = arr[j];
                          arr[j] = t;
            }
        }
    }
    float median;
    if (m % 2 == 1)
         median = (arr[m / 2]);
   } else {
   median = (arr[m / 2] + arr[m /2 - 1]) /2;
   }
   printf("%.2f",median);
   return 0;
   }
}