#include<iostream>
#include<vector>
#include<cstdlib>
#include<algorithm>
#include<climits>

std::vector<int> dist;
int ddist[1001][1001];
const long long INF = LLONG_MAX;
long long min_cost = INF;

void isCollect(long long cost, int n, int now, std::vector<bool> visited){
    if(min_cost < cost) return;
    if(n == 0){
        min_cost = std::min(min_cost, cost);
        return;
    }
    for(size_t i = now + 1; i < visited.size(); i++){
      if(visited[i] == false){
          visited[i] = true;
          isCollect(cost + ddist[now][i], n - 1, i, visited);
          visited[i] = false;
          break;
      }
    }
    for(int i = now - 1; i >= 0; i--){
        if(visited[i] == false){
            visited[i] = true;
            isCollect(cost + ddist[now][i], n - 1, i, visited);
            visited[i] = false;
            break;
        }
    }
}

int main(){
    int n, m;
    std::cin >> n >> m;

    dist.resize(m);
    for(int i = 0; i < m; i++){
        std::cin >> dist[i];
    }
    dist.push_back(0);

    std::sort(dist.begin(), dist.end());

    for(size_t i = 0; i < dist.size(); i++){
        for(size_t j = 0; j < dist.size(); j++){
            ddist[i][j] = std::abs(dist[i] - dist[j]);
        }
    }

    std::vector<bool> visited(dist.size(), false);
    int start = 0;
    for(size_t i = 0; i < dist.size(); i++){
        if(dist[i] == 0){
            start = i;
            visited[i] = true;
            break;
        }
    }

    std::vector<int> right;
    right.push_back(0);
    long long right_sum = 0;
    for(int i = start; i < dist.size() && i - start <= n; i++){
        int count = i - start;
        if(i - start == n){
            min_cost = std::min(min_cost, right_sum);
            break;
        }
        long long left_sum = 0;
        if(start - 1 >= 0) {
            left_sum = ddist[i][start - 1];
            count++;
        }
        for(int j = start - 2; j >= 0 && count < n; j--){
            left_sum += ddist[j + 1][j];
            count++;
        }
        if(count ==  n){
            min_cost = std::min(min_cost, right_sum + left_sum);
        }
        right_sum += ddist[i][i + 1];
    }

    right_sum = 0;
    for(int i = start; i >= 0 && i - start <= n; i--){
        int count = start - i;
        if(start - i == n){
            min_cost = std::min(min_cost, right_sum);
            break;
        }
        long long left_sum = 0;
        if(start - 1 >= 0) {
            left_sum = ddist[i][start + 1];
            count++;
        }
        for(int j = start + 2; j < dist.size() && count < n; j++){
            left_sum += ddist[j - 1][j];
            count++;
        }
        if(count ==  n){
            min_cost = std::min(min_cost, right_sum + left_sum);
        }
        if(i - 1 >= 0) right_sum += ddist[i][i - 1];
    }


    std::cout << min_cost << std::endl;
    return 0;
}