#include<vector>
#include<math.h>
#include<iostream>
#include<algorithm>
using namespace std;
#define MAXSIZE 15001

//1000000000

struct node{
    int A = 0;
    int B = 0;
    int C = 0;
    int D = 0;
    int L = 0;
    int book = 0;
};

std::vector<node> v;
std::vector<node> vAns;
std
 
::vector<int> inArr;
node nodeArr[MAXSIZE]; // TODO
int arr[MAXSIZE] = { 0 };
int ans[5][MAXSIZE] = { 0 };

int main()
{
    int n = 0, m = 0;
    int x = 0;
    int A = 0, B = 0, C = 0, D = 0;

    cin >> n >> m;

    for (int i = 1; i <= m; i++)
    {
        cin >> x;
        arr[x] += 1
 
;
        inArr.push_back(x);
        nodeArr[x].book = 1;
    }

    for (int L = 1; L < n; L++)
    {
        for (int i = 0; i < MAXSIZE; i++)
        {
            if (arr[i] >= 1)// 假設當前的點是A
            {   
                A = i;
                if (arr[A + 2 * L] >= 1)// B存在
                {
                    B = A + 2
 
 * L;
                    node temp;
                    temp.A = A;
                    temp.B = B;
                    temp.L = L;
                    v.push_back(temp);
                }
            }
        }
    }

    for (int i = 0; i < v.size(); i++)
    {
        for (int j = 1; j < n; j++)// TODO
        {
            if (v[i].B + 6 * v[i].L + j < n && arr[v[i].B + 6 * v[i].L + j] >= 1)// 找到ABCD成立的情況
            {
                v[i].C = v[i].B + 6 * v[i].L + j;
                if (v[i].B + 6 * v[i].L + j < n && arr[v[i].L + v[i].C] >= 1)
                {
                    v[i].D = v[i].L + v[i].C;
                    vAns.push_back(v[i]);
                    nodeArr[v[i].A].A += 1;
                    nodeArr[v[i].B].B += 1;
                    nodeArr[v[i].C].C += 1;
                    nodeArr[v[i].D].D += 1;

                    if (arr[v[i].A] > 1 || arr[v[i].B] > 1 || arr[v[i].C] > 1 || arr[v[i].D] > 1)
                    {
                        int temp1 = max(arr[v[i].A], arr[v[i].B]);
                        int temp2 = max(arr[v[i].C], arr[v[i].D]);
                        temp1 = max(temp1, temp2);

                        nodeArr[v[i].A].A *= temp1;
                        nodeArr[v[i].B].B *= temp1;
                        nodeArr[v[i].C].C *= temp1;
                        nodeArr[v[i].D].D *= temp1;
                    }

                    /*ans[1][v[i].A] += 1;
                    ans[2][v[i].B] += 1;
                    ans[3][v[i].C] += 1;
                    ans[4][v[i].D] += 1;*/
                }
            }
        }
    }

    //for (int i = 0; i < MAXSIZE; i++)
    //{
    //  if (arr[i] > 1)
    //  {
    //      vAns
    //  }
    //}

    for (int i = 0; i < inArr.size(); i++)
    {
        if (nodeArr[inArr[i]].book >= 1)
        {
            //if (arr[inArr[i]]>=)
            cout << nodeArr[inArr[i]].A << " " << nodeArr[inArr[i]].B << " " << nodeArr[inArr[i]].C << " " << nodeArr[inArr[i]].D << endl;
        }
    }


    return 0;
}