#include <bits/stdc++.h>

using namespace std;

typedef long long ll;

const int INF = 100000000;
int tmp;

struct G {
    int count;
    int now;
    int dis;
    vector<int> memo;
    G(int count, int now, int dis, vector<int> memo) : count(count), now(now), dis(dis), memo(memo) {}
    bool operator>(const G &g) const {
        return dis > g.dis;
        //else return count > g.count;       
    }
};

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    int n, m;
    cin >> n >> m;
    vector<int> d(m + 1, 0), minc(n + 1, INF);
    for (int i = 1; i <= m; i++) cin >> d[i];
    priority_queue<G, vector<G>, greater<G> > pq;
    pq.push(G(0, 0, 0, vector<int>(m + 1, 0)));
    while (!pq.empty()) {
        G g = pq.top();
        pq.pop();
        if (g.count > n) break;
        g.memo[g.now] = 1;
        minc[g.count] = min(minc[g.count], g.dis);
        for (int i = 1; i <= m; i++) {
            if (g.memo[i]) continue;
            if (minc[g.count + 1] == INF) {
                pq.push(G(g.count + 1, i, g.dis + abs(d[i] - d[g.now]), g.memo));
            }
        }
    }
    cout << minc[n] << "\n";
    return 0;
}