#include

#include

#include

#include

#include

#include

using namespace std;

const int N = 1e6 +10;

const int INF=0x3f3f3f;

int ans,l = 1,r,L,n,k,a[N];

bool check(int mid){

int sum = 1;

int last = a[1];

for(int i = 2;i<=n;i++){

if(a[i] - last >= mid){

sum ++;

last = a[i];

}

}

return sum >= k;

} int main(){

cin>>n>>k;

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

cin>>a[i];

sort(a+1,a+n+1);

r = a[n] - a[1];

while(l<=r){

int mid = l + r >>1;

if(check(mid)){

ans = mid;

l = mid + 1;

}

else

r = mid - 1;

}

cout<<ans;

}