#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++) {
        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 {
medain = (arr[m / 2] + arr[m /2 - 1])  /2;
}
printf("%.2f",median);
return 0;
}