1 #include<cstdio>
 2 #include<algorithm>
 3 using namespace std;
 4 #define maxn 1000000
 5 #define LL long long
 6 
 7 LL n,m,num[maxn],ans;
 8 
 9 inline void read(LL &now)
10 {
11     char ch=getchar(); now=0;
12     while(ch>‘9‘||ch<‘0‘) ch=getchar();
13     while(ch>=‘0‘&&ch<=‘9‘) now=now*10+ch-‘0‘,ch=getchar(); 
14 }
15 
16 bool check(LL x)
17 {
18     int t=1,tot=1;
19     for(int i=2;i<=n;i++)
20         if(num[i]-num[t]>=x) tot++,t=i;
21     return tot>=m?true:false;
22 }
23 
24 int main()
25 {
26     read(n); read(m);
27     LL l=0,r=0;
28     for(int i=1;i<=n;i++) read(num[i]);
29     sort(num+1,num+n+1);
30     r=num[n]-num[1];
31     while(l<r)
32     {
33         LL mid=(l+r)>>1;
34         if(check(mid)) ans=mid,l=mid+1;
35         else r=mid;
36     }
37     printf("%lld",ans);
38     return 0;
39 }