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


int compare (const void * a, const void * b)
{
    return ( *(int*)a - *(int*)b );
}

int main()
{
    int data[]= {9,8,7,10};
    const int LENGTH=4;
    qsort(data, LENGTH, sizeof(int), compare);
    for (int i=0; i<LENGTH; i++)
        printf("%d %d\n",i, data[i]);
    if (LENGTH%2) // length is odd
        printf("%d\n", data[LENGTH/2]);
    else // length is even - take average of middle two
        printf("%f\n", (data[LENGTH/2-1]+data[LENGTH/2])/2.0);
    return 0;
}