3SUM

input/code.cpp:7:10: fatal error: multiset: No such file or directory
    7 | #include <multiset>
      |          ^~~~~~~~~~
compilation terminated.

#include <iostream>
#include <algorithm>
#include <vector>
#include <cmath>
#include <queue>
#include <climits>
#include <multiset>
using namespace std;
typedef long long ll;
ll n;
vector<vector<ll>> capacity;
vector<vector<ll>> adj;

ll bfs(ll s, ll t, vector<ll>& parent) {
    fill(parent.begin(), parent.end(), -1);
    parent[s] = -2;
    queue<pair<ll, ll>> q;
    q.push({s, LLONG_MAX});
    
    while (!q.empty()) {
        ll cur = q.front().first;
        ll flow = q.front().second;
        q.pop();
        
        for (ll next : adj[cur]) {
            if (parent[next] == -1 && capacity[cur][next]) {
                parent[next] = cur;
                ll new_flow = min(flow, capacity[cur][next]);
                if (next == t) return new_flow;
                q.push({next, new_flow});
            }
        }
    }
    
    return 0;
}

ll maxflow(ll s, ll t) {
    ll flow = 0;
    vector<ll> parent(n + 1);
    ll new_flow;
    
    while (new_flow = bfs(s, t, parent)) {
        flow += new_flow;
        ll cur = t;
        while (cur != s) {
            ll prev = parent[cur];
            capacity[prev][cur] -= new_flow;
            capacity[cur][prev] += new_flow;
            cur = prev;
        }
    }
    
    return flow;
}

void task1(){
    ll s, t;
    cin >> s >> t;
    vector<ll> ints(s + 1);
    vector<ll> ints2(s + 1);
    multiset<ll> mp;

    for(ll i = 1; i <= s; i++){
        ll x;
        cin >> x;
        ints[i] = x;
        ints2[i] = x;
        mp.insert(x);
    } 

    vector<ll> temp;
    /*sort(ints.begin(), ints.end());
    int left = 1, right = s;
    for(int i = 1; i <= s; i++){
        while(left < right){
            ll sum = ints[left] + ints[right] + ints[i];
            if(sum == t && left != i && right != i){
                cout << left << " " << right << " " << i << endl;
                temp.push_back(ints[left]);
                temp.push_back(ints[right]);
                temp.push_back(ints[i]);

                 for(size_t i = 0; i < temp.size(); i++){
                    for(ll j = 1; j <= s; j++){
                        if(temp[i] == ints2[j]){
                            cout << j << " ";
                        }
                    }
                }
                return;
            }
            if(sum < t) left++;
            else right--;
        }
    }*/

    for(ll i = 1; i <= s; i++){
        for(ll j = i+1; j <= s; j++){
            mp.erase(ints[i]);
            mp.erase(ints[j]);
            ll need = t - ints[i] - ints[j];
            cout << need << endl;
            cout << ints[i] << " " << ints[j] << endl;
            if(mp.find(need) != mp.end()){
               // cout << i << " " << j << " " << mp[need] << endl;
                temp.push_back(need);
                temp.push_back(ints[j]);
                temp.push_back(ints[i]);

                for(size_t i = 0; i < temp.size(); i++){
                    for(ll j = 1; j <= s; j++){
                        if(temp[i] == ints2[j]){
                            cout << j << " ";
                        }
                    }
                }
                return;
            }
            
            mp.insert(ints[i]);
            mp.insert(ints[j]);
        }
    }
    






   
    cout << "IMPOSSIBLE" << endl;
}

void task2(){
     ll m;
    cin >> n >> m;
    capacity.assign(n + 1, vector<ll>(n + 1, 0));
    adj.assign(n + 1, vector<ll>());
    
    for (ll i = 0; i < m; i++) {
        ll a, b, c;
        cin >> a >> b >> c;
        capacity[a][b] += c;
        adj[a].push_back(b);
    }
}


int main() {
   task1();
}