#include <bits/stdc++.h>
using namespace std;
#define int long long
#define pll pair<long long, long long>
#define st string
#define fr first
#define sec second
#define pb push_back
#define beg begin
#define INF 1e18
#define MOD 1e9+7
void solve() {
int n,k;
cin >> n >> k;
int cnt = n-(n-k);
vector<int> a(n);
for(int i = 0; i < n; i ++)cin >> a[i];
if(n == k) cout << k;
else{
vector<int> b(n-1);
for(int i = 0; i < n-1; i++){
b[i] = abs(a[i] - a[i+1]);
}
sort(b.begin(),b.end());
for(int i = 0; i < n-k; i++){
cnt = cnt + b[i];
}
cout << cnt << endl;
}
}
signed main() {
ios::sync_with_stdio(false);cin.tie(nullptr);cout.tie(nullptr);cout << setprecision(20);
// freopen("input.txt", "r", stdin);
// freopen("output.txt", "w", stdout);
int T = 1;
//cin >> T;
while(T--) {
solve();
}
}
