include <bits/stdc++.h>

using namespace std; int a[100010]; int n, m;

bool check(int b) {

int cnt = 1, temp = 1;
for (int i = 2; i <= n; i++) {
	if (a[i] - a[temp] >= b) {
		temp = i;
		cnt++;
	}
}
return cnt >= m;

}

int main() {

cin >> n >> m;
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 = 0;
while (l <= r) {
	int mid = (l + r) / 2;
	if (check(mid)) {
		ans = mid;
		l = mid + 1;
	} else
		r = mid - 1;
}
cout << ans;
return 0;

}