#include<stdio.h>
int main(){
    int m,n;
    scanf("%d %d",&m, &n);
    if(m<=o||n<=0){
        printf("Inalid 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]=arr[j];
            arr[j]=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;
}