/**
* @file stove.cpp
* @brief https://oj.uz/problem/view/JOI18_stove
* @version 0.1
* @date 2022-06-27
*
*/
#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
using i16 = short;
using i32 = int;
using i64 = long long;
using u16 = unsigned short;
using u32 = unsigned int;
using u64 = unsigned long long;
int main() {
cin.tie(nullptr);
ios_base::sync_with_stdio(false);
u32 guests, matches, operation_time;
cin >> guests >> matches;
vector<u32> time(guests);
vector<u32> time_spaces(guests-1);
// READ DATA
cin >> time[0];
for (u32 i = 1; i < guests; i++) {
cin >> time[i];
time_spaces[i-1] = time[i] - time[i-1];
}
// PROCESS
sort(time_spaces.begin(), time_spaces.end(), greater<int>());
// Turn on the first time
operation_time = 1;
matches -= 1;
for (u32 i = 0; i < time_spaces.size(); i++)
{
if (matches > 0) {
operation_time ++;
matches --;
} else {
operation_time += time_spaces[i];
}
}
cout << operation_time << '\n';
return 0;
}
