USACO-T011: Barn Repair

/*
ID: mickyta1
TASK: barn1
LANG: C++
*/

#include <bits/stdc++.h>
using namespace std;

const int N = 200;

int cows[N + 1];
vector<int> edges;

int main(){

    freopen("barn1.in", "r", stdin);
    freopen("barn1.out", "w", stdout);

    int limBoard, nCow;
    scanf("%d%*d%d", &limBoard, &nCow);
    if(nCow <= limBoard){
        cout << nCow << '\n';
        return 0;
    }
    for(int i = 1; i <= nCow; ++i){
        scanf("%d", &cows[i]);
    }
    sort(cows + 1, cows + nCow + 1);
    for(int i = 1; i < nCow; ++i){
        edges.push_back(cows[i + 1] - cows[i] - 1);
    }
    sort(edges.begin(), edges.end());
    int compCnt = nCow;
    int sum = nCow;
    for(int &w : edges){
        sum += w;
        --compCnt;
        if(compCnt == limBoard){
            break;
        }
    }
    cout << sum << '\n';

    fclose(stdin);
    fclose(stdout);

    return 0;
}