#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++) {
        float x;
    for(int j = 0; j < n; j++) {
        fload 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;
}