#include <stdio.h>
#include <stdlib.h>

int compare(const void *a, const void *b) {
    if(*(long long *)a >*(long long *)b) return 1;
    else return -1;
}

long long num[200001];
int main() {
    int n,c;
    scanf("%d %d",&n, &c);
    for(int i=0; i<n; i++) {
        scanf("%lld",&num[i]);
    }
    qsort(num,n,sizeof(long long),compare);
    //최소 간격
    long long low=1;
    long long res=0;
    //최대 간격
    long long high=num[n-1]-num[0];
    //이분탐색
    while(low<=high) {
        long long mid=(low+high)/2;
        //공유기 갯수
        int cnt = 1; 
        long long start=num[0];
        for(int i=1; i<n; i++) {
            //간격이 mid보다 클때
            if(num[i]-start>=mid) {
                cnt++;
                start=num[i];
            }
        }
        //공유기 수가 같거나 많을때
        if(cnt>=c) {
            res=mid;
            low=mid+1;
        } else {
            high = mid -1;
        }
    }
    printf("%lld",res);
    return 0;
}