#include <bits/stdc++.h>
using namespace std;
long long n, m, k;
vector<long long> arr;
void solve() {
  cin >> n >> m >> k;
  arr.resize(n);
  for (long long i = 0; i < n; i++) cin >> arr[i];
  vector<long long> b;
  long long l = arr[n - 1] - arr[0];
  ;
  for (int i = 1; i < n; i++) {
    b.push_back(arr[i] - arr[i - 1]);
  }
  sort(b.begin(), b.end());
  long long i = b.size() - 1;
  int ctr = k - 1;
  for (; ctr > 0; i--, ctr--) {
    l -= b[i];
    l += 1;
  }
  l++;
  cout << l << endl;
}
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 1;
  while (t--) {
    solve();
  }
  return 0;
}
