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

std::vector<int> dist;
int ddist[1001][1001];

bool isCollect(long long cost, int n, int now, std::vector<bool> visited){
    if(cost < 0) return false;
    if(n == 0) return true;
    int min = 9999999, min2 = 9999999;
    int min_index = 0, min2_index = 1;
    for(int i = 0; i < visited.size(); i++){
        if(visited[i] == false){
            if(ddist[now][i] < min){
                min2 = min;
                min2_index = min_index;
                min = ddist[now][i];
                min_index = i;
            }
            if(ddist[now][i] < min2){
                min2 = ddist[now][i];
                min2_index = i;
            }
        }
    }
    if(visited[min_index] == false){
        visited[min_index] = true;
        bool result  = isCollect(cost - ddist[now][min_index], n - 1, min_index, visited);
        if(result) return true;
        visited[min_index] = false;
    }
    if(visited[min2_index] == false){
        visited[min2_index] = true;
        bool result = isCollect(cost - ddist[now][min2_index], n - 1, min2_index, visited);
        if(result) return true;
        visited[min2_index] = false;
    }
    return false;
}

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;
        }
    }

    long long high = 100000000, low = 0;

    while(high - low > 1){
        long long mid = (high + low) / 2;
        if(isCollect(mid, n, start, visited)){
            high = mid;
        }else{
            low = mid;
        }
    }

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