#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl
inline int power(int a, int b) {
    int x = 1;
    while (b) {
        if (b & 1) x *= a;
        a *= a;
        b >>= 1;
    }
    return x;
}


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

//_ ***************************** START Below *******************************

vector<int> a;

bool isPossible(int n, int k, vector<int>& a, int mid){
    int cows = 1;
    for(int i=0; i<n; ){
        int j = i+1;
        while(j<n && a[j] - a[i] < mid) j++;
        if(j==n) break;
        cows++;
        i = j;
    }
    return cows>=k; 
}

int consistency1(int n, int k){
	vector<int> b(a);
    sort(begin(b), end(b));

    int s = 0, e = INF;
    int ans = 0;
    while(s<=e){
        int mid = s + (e-s)/2;
        if(isPossible(n, k, b, mid)){
            ans = max(ans, mid);
            s = mid+1;
        }
        else{ 
            e = mid-1;
        }

    }

    return ans;

}



int consistency2(int n, int k){
	
	vector<int> b(a);
	
	sort(begin(b), end(b));
	
	int s = 0, e = INF;
	
	while(s<e){
		int mid = s + (e-s+1)/2;
		if(isPossible(n, k, b, mid)){
			s = mid;
		}
		else e = mid-1;
	}
	
	return e;
	
}













bool isPoss(int n, int k, int mid){
	
	int ct = 1;
	
	for(int i=0; i<n; ){
		int j = i+1;
		while(j<n && a[j] - a[i] < mid) j++;
		if(j==n) break;
		
		ct++;
		i = j;
	}
	
	return ct >= k;
}

int practice(int n, int k){
	sort(begin(a), end(a));
	
	int s = 0, e = INF;
	while(s<e){
		int mid = s + (e-s+1)/2;
		if(isPoss(n, k, mid)){
			s = mid;
		}
		else e = mid-1;
	}
	
	
	return e;
	
}





void solve() {
	
    int n, k;
    cin>>n >> k;
    a.resize(n);
    
    for(int i=0; i<n; i++) cin >> a[i];
    // cout << consistency1(n, k) << " " << consistency2(n,k) << endl;

    cout << consistency1(n, k) << " -> " << practice(n, k) << endl;

}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}