414v1

#include <iostream>
//#include <chrono>
//#include <fstream>
//#include <bits/stdc++.h>
#include <vector>
#include <algorithm>

#define mp make_pair
#define pb push_back
#define eb emplace_back
#define x first
#define y second
#define sz(x) (int)x.size()
#define all(x) begin(x), end(x)
#define rall(x) rbegin(x), rend(x)

using namespace std;

typedef unsigned long long ull;
typedef long long ll;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;

int n_deer, n_elf;
vector<pi> deer, elf;
vector<vector<int>> last_res;

bool check(int len) {
    int st = 0;
    int end = 1;
    int cur_d = 0;
    int count = 0;
    vector<bool> used(n_elf);
    while (st < n_elf && end < n_elf && cur_d < n_deer) {
        if (!used[st] && elf[st].x < deer[cur_d].x && deer[cur_d].x < elf[end].x) {
            last_res[count][0] = deer[cur_d].y;
            last_res[count][1] = elf[st].y;
            last_res[count][2] = elf[end].y;
            count++;
            used[end] = 1;
            st++, end++;
            cur_d++;
        }
        else if (deer[cur_d].x >= elf[end].x)
            end++;
        else if (elf[st].x >= deer[cur_d].x)
            cur_d++;
        else if (used[st])
            st++;
        /*else if (elf[st].x >= deer[cur_d].x)
        st++;
        else if (deer[cur_d].x >= elf[end].x)
        end++;*/
    }
    /*while (st < n_elf) {
        if (elf[st].x < deer[cur_d].x && deer[cur_d].x < elf[end].x) {
            last_res[count][0] = deer[cur_d].y;
            last_res[count][1] = elf[st].y;
            last_res[count][2] = elf[end].y;
            count++;
            st++, end++;
            cur_d++;
            used[end] = 1;
        }
        else {
            st++;
        }
    }*/
    return count >= len;
}

int main() {
    /*ifstream cin("in.txt");
    ofstream cout("out.txt");
    auto start_time = chrono::high_resolution_clock::now();*/

    ios::sync_with_stdio(false);
    cin.tie(0);
    cout.tie(0);

    cin >> n_deer >> n_elf;
    deer.assign(n_deer, pi());
    elf.assign(n_elf, pi());
    last_res.assign(n_deer, vector<int>(3));
    for (int i = 0; i < n_deer; i++) {
        cin >> deer[i].x;
        deer[i].y = i + 1;
    }
    for (int i = 0; i < n_elf; i++) {
        cin >> elf[i].x;
        elf[i].y = i + 1;
    }
    sort(all(deer), [](pi a, pi b) {
        return a.x < b.x;
    });
    sort(all(elf), [](pi a, pi b) {
        return a.x < b.x;
    });

    int l = 0, r = n_deer + 1;
    while (l + 1 < r) {
        int mid = (l + r) / 2;
        if (check(mid))
            l = mid;
        else
            r = mid;
    }
    cout << l << "\n";
    for (int i = 0; i < l; i++) {
        for (int j = 0; j < 3; j++)
            cout << last_res[i][j] << " ";
        cout << "\n";
    }

    /*auto end_time = chrono::high_resolution_clock::now();
    chrono::duration<double> duration = end_time - start_time;
    cout << duration.count() << "\n";
    cin.close();
    cout.close();*/
    return 0;
}