#include <bits/stdc++.h>
using namespace std;
#define FastIO ios_base::sync_with_stdio(0);cin.tie(nullptr);
#define MULTEST int t;cin >> t;while (t--) solve();
#define rf(__abc__) freopen(__abc__".inp","r",stdin);freopen(__abc__".out","w",stdout);
const int mod = 1e9 + 7;
long long pw(long long x,long long y) {
if (y == 0) return 1;
if (y % 2 == 0) {
long long a = pw(x,y/2);
return a*a%mod;
} else {
long long a = pw(x,y - 1);
return a*x%mod;
}
}
int add(int x,int y) {
x += y;
if (x >= mod) x -= mod;
return x;
}
int subtract(int x,int y) {
x -= y;
if (x < 0) x += mod;
return x;
}
int mul(long long x,int y) {
x *= y;
if (x >= mod) x %= mod;
return x;
}
///Code goes here
int n,k;
int arr[100009],temp[100009];
int main() {
FastIO;
cin >> n >> k;
for (int i = 1;i <= n;i++) cin >> arr[i];
sort(arr + 1,arr + 1 + n);
int ret = arr[n] - arr[1];
for (int i = 2;i <= n;i++) {
temp[i - 1] = arr[i] - arr[i - 1];
}
sort(temp + 1,temp + n,greater <int>());
for (int i = 1;i < k;i++) ret -= temp[i];
cout << ret + k;
return 0;
}
