hulabitetmung

#include <iostream>
#include <vector>
#include <algorithm>
#include <math.h>
#include <map>

#define LIM 1005
#define ll long long 

using namespace std;

typedef pair<int, int> pii;

int n, X;
int a[LIM];
map <int, vector<pii>> sum;

vector <int> ans;

void Process() {
    for (int i = 1; i < n; i++) {
        for (int j = 0; j < i; j++) {
            int cursum = a[i] + a[j];
            int expect = X - cursum;

            if (sum.count(expect) > 0) {
                for (auto k : sum[expect]) {
                    if (k.first != i && k.first != j && k.second != i && k.second != j) {
                        ans.push_back(i);
                        ans.push_back(j);
                        ans.push_back(k.first);
                        ans.push_back(k.second);
                        return;
                    }
                }
            }
            
            sum[cursum].push_back({i, j});
        }
    }
}

int main() {
    ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
    
    cin >> n >> X;

    for (int i = 0; i < n; i++) cin >> a[i];

    Process();

    if (ans.size() > 0) {
        sort(ans.begin(), ans.end());
        for (auto i : ans) cout << i + 1 << " ";
    }
    else {
        cout << "IMPOSSIBLE";
    }
      

    return 0;
}