#include<iostream>

#include<vector>

using namespace std;

#define SIZE 200001

int arr[SIZE], n;

int cal(int len){

int cnt = 1, pos = arr[0];

for(int i = 1; i < n; i++){

if(arr[i] - pos >= len){

cnt++;

pos = arr[i];

}

}

return cnt;

}

int main(){

freopen("input.txt", "rt", stdin);

int c, lt = 0, rt = -2147000000, mid = 0, res = 0;

cin>>n>>c;

for(int i = 0; i < n; i++){

cin>>arr[i];

if(arr[i] > rt) rt = arr[i];

}

sort(arr, arr+n);

while(lt <= rt){

mid = (lt + rt) / 2;

if(cal(mid) >= c){

res = mid;

lt = mid + 1;

}else{

rt = mid - 1;

}

}

cout<<res<<"\n";

return 0;

}