#include <bits/stdc++.h>
using namespace std;
using ll=long long;
#define in insert
#define pb push_back
int main(){
ll n,k;
cin>>n>>k;
vector<ll>v(n);
for(int i=0;i<n;i++){
cin>>v[i];
}
sort(v.begin(),v.end());
ll say;
ll ans=LLONG_MAX;
ll temp;
for(int i=0;i<(1<<n);i++){
say=0;
temp=0;
for(int j=0;j<n;j++){
if((i&(1<<j))!=0){
say++;
}
}
if(say!=k || (i&1)==0) continue;
ll last=v[0];
ll curr;
for(int j=1;j<n;j++){
if((i&(1<<j))!=0){
curr=v[j-1]+1;
temp+=curr-last;
last=v[j];
}
if(j==n-1){
temp+=v[j]+1-last;
break;
}
}
ans=min(ans,temp);
}
cout<<ans;
}
