#include <iostream>
#include <algorithm>
using namespace std;

int main()
{
    int N,K,n[9];
    cin >> N >> K;
    for(int i = 0; i < N; i++)
        cin >> n[i];

    cout <<  *max_element(n,n+K)-*min_element(n,n+K) << endl;
    return 0;
}