#include<stdio.h>
#include<stdlib.h>

int cmpfunc(cout void*a,const void*b)
{
    float fa=*(float*)a;
    float fb=*(float*)b;
    if(fa<fb)return -1;
    if(fa>fb)return 1;
    return 0;
}
int main(){
    int n, m;
    scanf("%d",&n);
    scanf("%d",&m);
    if(n<=0||m<=0)
    {
        printf("Invalid Input\n");
        return 0;
        float arr[n];
        for(int i=0;i<n;i++)
        {
            for(int j=0;j<m;j++)
            {
                float temp;
                scanf("%f",&temp);
                if(j==0)arr[i]=temp;
            }
        }
        qsort(arr,n,sizeof(float),cmpfunc);
        float median;
        if(n%2==1)
        {
            median=arr[n/2];
        }
        else
        {
            median=(arr[(n-1)/2]+arr[n/2]/2.0;)
        }
        printf("%.2f\n",median);
    }
}