cow

#include<bits/stdc++.h>
#define MAXN 100010

using namespace std;

vector<int> baias;

bool valida(int d, int k){
    int pos = v[0];
    while(k > 1){
        if(lower_bound(baias.begin(),baias.end(),pos+d) == baias.end()) return false;
        pos = *lower_bound(baias.begin(),baias.end(),pos+d);
        k--;
    }
    return true;
}

int main() {

    int n, k; scanf("%d %d", &n, &k);

    for(int i = 0; i < n; i++){
        int aux; scanf("%d", &aux);
        baias.push_back(aux);
    }

    int l = 1;
    int r = v[n-1]-v[0]+1;

    while(l < r){
        int meio = (l+r+1)/2;
        if(valida(meio, k)){
            l = meio;
        }
        else{
            r = meio-1;
        }
    }

    printf("%d", l);
}