#include<stdio.h>
#include<stdlib.h>
int compare(const void *a,const void *b){
    float fa =*(const float*) a;
    float fb =*(const flota*) b;
    return (fa > fb) - (fa < fb);
}
int main(){
    int M,N;
    if(scanf("%d %d",&M,&N) != 2){
        printf("InvalID Input\n");
        return 0;
    }
if(M <=0||N<=0){
    printf("Invalid Input\n");
    return 0;
}
float first_column_prices[M];
float temp_price;
for(int i=0;i<M;i++){
    for(int j=0;j<N;j++){
        if(scanf("%f",&temp_price)
        printf("Invalid Input\n");
        return 0;
    }
    if(temp_price<0){
        printf("Invalid input\n");
        return 0;
    }
    if(j==0){
        first_column_price;
    }
  }
}
qsort(first_column_prices,M,sizeof(float),compare);
float median;
if(M % 2 = = 1){
    median=first_column_prices[M/2];
}else{
    median = (first_column_prices[M/2 -1]+ FIRST_COLUMN[M/2]) / 2.0;
}
printf("%,2f\n",median);
return 0;
}