#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
#include <bits/stdc++.h>
#define fi first
#define se second
#define pb push_back
#define sz(a) (int)a.size()
#define all(a) a.begin(), a.end()
#define rall(a) a.rbegin(), a.rend()
#define ff(i,a,b) for(int i=a;i<=b;i++)
#define fb(i,b,a) for(int i=b;i>=a;i--)
using namespace std;
using namespace __gnu_pbds;
typedef long long ll;
typedef pair<int,int> pii;
const int maxn = 100005;
const int inf = 1e9 + 5;
template<typename T>
using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
// os.order_of_key(k) the number of elements in the os less than k
// *os.find_by_order(k) print the k-th smallest number in os(0-based)
int n, K;
int niz[maxn];
int main()
{
ios::sync_with_stdio(false);
cout.tie(nullptr);
cin.tie(nullptr);
cin >> n >> K;
ff(i,1,n)cin >> niz[i];
vector<int> vec;
ff(i,2,n)vec.pb(niz[i] - niz[i - 1]);
ll zbir = 0;
for(auto c : vec)zbir += c;
K -= 1;
sort(rall(vec));
ff(i,0,min(K, sz(vec)) - 1) {
zbir -= vec[i];
}
cout << zbir + K + 1 << endl;
return 0;
}
/**
// probati bojenje sahovski ili slicno
**/
