#include <iostream>
#include <vector>
#include <set>
#include <map>
#include <algorithm>
#define fori(n) for(int i = 0; i < n; ++i)
#define forj(n) for(int j = 0; j < n; ++j)
#define forr(n) for(int i = n - 1; i >= 0; --i)
#define forEach(array) for(auto &item : array)
#define printSpace(a) cout << a << " "
#define printSpace2(a, b) cout << a << " " << b << " "
#define printSpace3(a, b, c) cout << a << " " << b << " " << c << " "
#define printSpace4(a, b, c, d) cout << a << " " << b << " " << c << " " << d <<" "
#define printSpace5(a, b, c, d, e) cout << a << " "<< b << " " << c << " " << d <<" " << e << " "
#define printSpace6(a, b, c, d, e, f) cout << a << " "<< b << " " << c << " " << d <<" "<< e << " " << f << " "
#define printLn(n) cout << n << '\n'
#define printNL() cout <<'\n'
#define print(n) cout << n
using namespace std;
typedef long long ll;
struct CompressedLetter {
ll num;
char letter;
};
ll readLL();
string readStr();
void resolve();
void resolveTest();
bool isPrime(ll n);
vector<bool> detectPrimes(ll n);
ll minPosInArray(const vector<ll> &nums);
ll maxPosInArray(const vector<ll> &nums);
ll minValInArray(const vector<ll> &nums);
ll maxValInArray(const vector<ll> &nums);
vector<ll> calcPrefixSum(const vector<ll> &nums);
vector<ll> calcSuffixSum(const vector<ll> &nums);
vector<ll> getDigits(ll n);
ll sumNumRange(ll start, ll finish);
ll calcNumLength(ll n);
vector<CompressedLetter> processCompressedStr(const string &str);
int main() {
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
resolve();
return 0;
}
void resolve() {
ll pointNum = readLL();
ll possibleDelete = readLL() - 1;
if (pointNum == 1) {
printLn(1);
return;
}
vector<ll> points(pointNum);
forEach(points) {
item = readLL();
}
sort(points.begin(), points.end());
ll res = points[pointNum - 1] - points[0] + 1;
vector<ll> segments(pointNum - 1);
for (ll i = 1; i < pointNum; ++i) {
segments[i - 1] = points[i] - points[i - 1] - 1;
}
sort(segments.begin(), segments.end());
possibleDelete = min(possibleDelete, (ll) segments.size());
for (ll i = (ll) segments.size() - 1; possibleDelete; --i, --possibleDelete) {
res -= segments[i];
}
printLn(res);
}
ll readLL() {
ll num;
cin >> num;
return num;
}
string readStr() {
string str;
cin >> str;
return str;
}
bool isPrime(ll n) {
if (n == 0 || n == 1) {
return false;
}
for (ll i = 2; i * i <= n; ++i) {
if (n % i == 0) {
return false;
}
}
return true;
}
vector<bool> detectPrimes(ll n) {
vector<bool> nums(n + 1, true);
nums[0] = false;
nums[1] = false;
for (ll i = 2; i <= n; ++i) {
if (nums[i]) {
for (ll j = i * i; j <= n; j += i) {
nums[j] = false;
}
}
}
return nums;
}
ll minPosInArray(const vector<ll> &nums) {
ll pos = 0;
for (ll i = 1; i < nums.size(); ++i) {
if (nums[pos] > nums[i]) {
pos = i;
}
}
return pos;
}
ll maxPosInArray(const vector<ll> &nums) {
ll pos = 0;
for (ll i = 1; i < nums.size(); ++i) {
if (nums[pos] < nums[i]) {
pos = i;
}
}
return pos;
}
vector<ll> getDigits(ll n) {
vector<ll> digits;
while (n > 0) {
digits.push_back(n % 10);
n /= 10;
}
return digits;
}
vector<ll> calcPrefixSum(const vector<ll> &nums) {
vector<ll> prefix(nums.size());
prefix[0] = nums[0];
for (ll i = 1; i < nums.size(); ++i) {
prefix[i] = prefix[i - 1] + nums[i];
}
return prefix;
}
vector<ll> calcSuffixSum(const vector<ll> &nums) {
vector<ll> suffix(nums.size());
suffix[nums.size() - 1] = nums[nums.size() - 1];
for (ll i = (ll) nums.size() - 2; i >= 0; --i) {
suffix[i] = suffix[i + 1] + nums[i];
}
return suffix;
}
ll sumNumRange(ll start, ll finish) {
if (finish < start) {
return 0;
}
if (start > 1) {
return sumNumRange(1, finish) - sumNumRange(1, start - 1);
}
if (finish % 2 == 1L) {
return sumNumRange(1, finish - 1) + finish;
} else {
return finish * (finish + 1) / 2;
}
}
vector<CompressedLetter> processCompressedStr(const string &str) {
vector<CompressedLetter> res;
ll pos = 0;
while (pos < str.length()) {
ll numLength = 0;
while ('0' <= str[pos] && str[pos] <= '9') {
numLength++;
pos++;
}
if (numLength == 0) {
res.push_back({1, str[pos]});
} else {
res.push_back({stoi(str.substr(pos, numLength)), str[pos + numLength]});
}
pos += numLength + 1;
}
return res;
}
ll calcNumLength(ll n) {
ll res = 0;
while (n > 0) {
n /= 10;
res++;
}
return res;
}
ll minValInArray(const vector<ll> &nums) {
return nums[minPosInArray(nums)];
}
ll maxValInArray(const vector<ll> &nums) {
return nums[maxPosInArray(nums)];
}
