// File stove.cpp created on 02.10.2025 at 19:11:48
#include <bits/stdc++.h>
using i64 = long long;
#ifdef DEBUG
#include "/home/ahmetalp/Desktop/Workplace/debug.h"
#else
#define debug(...) void(23)
#endif
int main() {
std::ios::sync_with_stdio(false);
std::cin.tie(nullptr);
int N, K;
std::cin >> N >> K;
std::vector<int> A(N);
for (int i = 0; i < N; ++i) {
std::cin >> A[i];
}
std::sort(A.begin(), A.end());
std::vector<int> d(N - 1);
for (int i = 0; i < N - 1; ++i) {
d[i] = A[i + 1] - A[i] - 1;
}
std::sort(d.begin(), d.end());
i64 ans = N;
for (int i = 0; i < N - K; ++i) {
ans += d[i];
}
std::cout << ans << '\n';
return 0;
}
