#include<bits/stdc++.h>
using namespace std;
int n, c, a[100005];
int func(int x){
int cnt = 1;
int fx = a[1];
for(int i = 2; i <= n; i++) {
if(a[i] - fx >= x){
cnt++;
fx = a[i];
}
}
return cnt;
}
int main(){
cin >> n >> c;
for(int i = 1; i <= n; i++) {
cin >> a[i];
}
sort(a + 1, a + n + 1);
int l = 1, r = a[n] - a[1], ans;
while(l <= r){
int mid = (l + r) / 2;
if(func(mid) >= c){
l = mid + 1;
ans = mid;
} else {
r = mid - 1;
}
}
cout << ans;
return 0;
}
