#include <bits/stdc++.h>
using namespace std;
long long prime[1000005];
long long fac[1000005];
int mul(int a, int b) {
  int res = 0;
  while (b) {
    if (b & 1) res = (res + a);
    a = (a + a);
    b = b / 2;
  }
  return res;
}
int bexp(int a, int b) {
  int res = 1;
  while (b) {
    if (b & 1) res = mul(res, a);
    a = mul(a, a);
    b = b / 2;
  }
  return res;
}
int inv(int a) { return bexp(a, 1000000007 - 2); }
int nCr(int n, int r) { return mul(fac[n], mul(inv(fac[n - r]), inv(fac[r]))); }
long long power(long long a, long long b, long long c) {
  long long res = 1;
  while (b) {
    if (b & 1) res = (res * a) % c;
    a = (a * a) % c;
    b /= 2;
  }
  return res % c;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n, m, k;
  cin >> n >> m >> k;
  long long a[n];
  vector<pair<long long, long long>> v;
  for (int i = 1; i <= n; i++) {
    cin >> a[i];
  }
  long long p = n - k;
  if (p == 0) {
    cout << n << endl;
    return 0;
  }
  for (int i = 2; i <= n; i++)
    v.push_back(make_pair(a[i] - a[i - 1] + 1, i - 1));
  sort(v.begin(), v.end());
  long long count = 0;
  long long sum = 0;
  vector<pair<long long, long long>> final;
  for (int i = 0; i < v.size(); i++) {
    sum += v[i].first;
    final.push_back(make_pair(v[i].second, v[i].first));
    count++;
    if (count == p) break;
  }
  long long check = 2;
  sort(final.begin(), final.end());
  for (int i = 1; i < final.size(); i++) {
    if (final[i].first - final[i - 1].first == 1) {
      sum -= 1;
      check += 1;
    } else
      check += 2;
  }
  cout << sum + n - check << endl;
}
