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