/*
* Created: 2022-07-01 13:42
*/
#include <bits/stdc++.h>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
using namespace std;
using namespace chrono;
// using namespace atcoder
template <typename T>
using ordered_set =
tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
typedef long long ll;
typedef long double ld;
const ll inf = 1e18;
#define pii pair<int,int>
#define pll pair<ll,ll>
#define vi vector<int>
#define vll vector<ll>
#define rep(i, a, b) for(int i = (a);i<(b);i++)
#define repn(i, a, b) for(int i = (a);i>=(b);i--)
#define ss second
#define ff first
#define mkp make_pair
#define pb push_back
#define all(x) (x).begin(), (x).end()
void solve() {
int n, k;
cin >> n >> k;
ll a[n];
rep(i, 0, n)cin >> a[i];
ll d[n-1];
rep(i, 1, n)d[i-1]=a[i]-a[i-1];
sort(d, d+n-1);
long long sum = k;
for(int i = 0;i<n-k;i++)sum+=d[i];
cout<<sum<<"\n";
}
int main () {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int t = 1;
while(t--) {
solve();
}
return 0;
}
