# include<stdio.h>
int compare(const void*a,const void*b){
    floatx=*(float *)a;
    float y=*(float*)b;
    if(x<y)return-1;
    if(x>y)return1;
    return 0;
}
int main()
{
    int M,N;
    scanf("%d %d",&M,%N);
    if(M <=0 || N<=0){
        printf("Invalid input");
        return 0;
        float matrix[M][N];
        float firstcoll[M];
        for(int i=0;i<M;i++){
            for(int j=0;j<N;j++){
                scanf("%d",&matrix[i][j]);
                if(matrix[i][j]<0){
                    printf("Invalid input");
                    return 0;
                }
                if(i==0){
                    firstcoll[i]=matrix[i][j];
                }
            }
        }
        qsort(firstcol,M,sizeof(float),compare);
        float median;
        if(M%2==1){
            median=firstcol[(M/2)-1]+firstcol[M/2])/2.0;
        } else{
            median=(firstcol([M/2)-1]+firstcol[M/2])/2.0;
        }
        printf("%2f",median);
        return 0;
    }