#include<cstdio>
#include<algorithm>
using namespace std;
const int inf=0x7fffffff;
int n,m,a[100001];
int solve(){
    int l=0,r=inf,mid,now,tot;
    while(l<r){
        mid=(l+r+1)>>1;
        now=a[1];
        tot=1;
        for(int i=2;i<=n;++i){
            if(a[i]-now>=mid)now=a[i],++tot;
            if(tot>=m)break;
        }
        if(tot<m)r=mid-1;
        else l=mid;
    }
    return l;
}
int main(){
    scanf("%d%d",&n,&m);
    for(int i=1;i<=n;++i)scanf("%d",&a[i]);
    sort(a+1,a+n+1);
    printf("%d",solve());
}