#include <bits/stdc++.h>
using namespace std;
#define int              long long int
#define double           long double
#define print(a)         for(auto x : a) cout << x << " "; cout << endl


const int M = 1000000007;
const int N = 3e5+9;
const int INF = 2e9+1;
const int LINF = 2000000000000000001;

inline int power(int a, int b) {
    int x = 1;
    a %= M;
    while (b) {
        if (b & 1) x = (x * a) % M; 
        a = (a * a) % M;
        b >>= 1;
    }
    return x;
}


//_ ***************************** START Below *******************************




vector<int> a;

int consistency(int n, int m, int k){

    vector<int> dif;
    for(int i=1; i<n; i++){
        dif.push_back(a[i] - a[i-1] - 1);
    }
    sort(begin(dif), end(dif));

    int ans = n;
    for(int i=0; i<n-k; i++){
        ans += dif[i];
    }

    return ans;    
}















int practice(int n, int m, int k){


    return 0;
}





void solve() {
    
    int n, m, k;
    cin>> n >> m >> k;
    
    a.resize(n);
    for(int i=0; i<n; i++) cin >> a[i];
    
    cout << consistency(n, m, k) << endl;


}





int32_t main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);

    int t = 1;
    // cin >> t;
    while (t--) {
        solve();
    }

    return 0;
}