#include <bits/stdc++.h>
using namespace std;
#define int long long
#define ll long long
#define pii pair <int, int>
#define pb push_back
#define mp make_pair
#define dbg puts("dbg");
#define outp(x) cout << #x << " = " << (x) << endl
#define all(x) (x).begin(), (x).end()
#define test int t; cin >> t; while(t--){solve();}
#define MOD 998244353
int fpb(int a,int b){if(b == 0){return a;}return fpb(b, a%b);}
int kpk(int a,int b){return (a*b)/fpb(a, b);}
int n, k, t[100003], totGroupNow, par[100003];
vector <pair <int, pii>> v;
int root(int x){
if(par[x] == x){
return x;
}
par[x] = root(par[x]);
return par[x];
}
void join(int x, int y){
par[root(x)] = root(y);
}
bool cek(int x, int y){
return (root(x) == root(y));
}
void solve(){
cin >> n >> k;
for(int i=1; i<=n; i++){
cin >> t[i];
}
for(int i=2; i<=n; i++){
v.pb({t[i]-t[i-1], {i-1, i}});
}
sort(all(v));
totGroupNow = n;
for(int i=1; i<=n; i++){
par[i] = i;
}
for(auto i : v){
if(totGroupNow == k) break;
join(i.second.first, i.second.second);
totGroupNow--;
}
int mini = t[1], maxi = t[1], res = 0;
for(int i=2; i<=n+1; i++){
if(cek(i-1, i)){
maxi = t[i];
} else {
res += maxi - mini + 1;
mini = t[i], maxi = t[i];
}
// cout << mini << " " << maxi << endl;
}
cout << res << endl;
}
int32_t main() {
ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
solve();
return 0;
}
