#include <bits/stdc++.h>
#define int long long
#define pii pair<int, int>
#define fi first
#define se second
using namespace std;
const int N = 5e6 + 5;
const int MOD = 1e9 + 7;
const int inf = 1e18;
int n, k;
int a[N], b[N];
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
cin >> n >> k;
for (int i=1; i<=n; ++i) {
cin >> a[i];
}
sort(a+1, a+n+1);
for (int i=1; i<n; ++i) {
b[i]=a[i+1]-a[i]-1;
}
sort(b+1, b+n);
int sum=n;
for (int i=1; i<=n-k; ++i) {
sum+=b[i];
}
cout << sum;
return 0;
}
