自己看

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
ll n,k;
ll a[200010];
int main(){
    //freopen(".in","r",stdin);
	//freopen(".out","w",stdout);
	std::ios::sync_with_stdio(false);
	std::cin.tie(nullptr);
	std::cout.tie(nullptr);
    cin>>n>>k;
    for(ll i=1;i<=n;i++){
        cin>>a[i];
    }
    sort(a+1,a+1+n);
    ll ans=1e18;
    for(ll i=1;i+k<=n;i++){
        ans=min(ans,a[i+k-1]-a[i]);
    }
    cout<<ans<<endl;
    //fclose(stdin);
	//fclose(stdout);
	return 0;
}
//coder::by::M91