#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int N, K;
cin >> N >> K;
vector<long long> value(N);
for (int i = 0; i < N; i++) cin >> value[i];
sort(value.begin(), value.end());
vector<long long> diff;
for (int i = 0; i < N - 1; i++) diff.push_back(value[i + 1] - value[i] - 1);
sort(diff.begin(), diff.end());
long long res = value[N - 1] - value[0] + 1;
K--;
for (int i = N - 2; i >= 0 && K > 0; i--) {
res -= diff[i];
K--;
}
cout << res << '\n';
return 0;
}
