#include <iostream>
#include <algorithm>

using namespace std;

int main()
{
    int n, x;
    cin >> n >> x;
    pair<int, int> niza[n];
    for(int i = 0; i < n; i++)
    {
        cin >> niza[i].first;
        niza[i].second = i;
    }
    sort(niza, niza + n);
    int s = 0, e = n - 1;
    int o = -1, p = -1;
    while(s < e)
    {
        if(niza[s].first + niza[e].first == x)
        {
            cout << niza[s].second + 1<< " " << niza[e].second + 1<< endl;
            return 0;
        }
        else if(niza[s].first + niza[e].first < x)
        {
            s++;
        }
        else{e--;}
    }
    
        cout << "IMPOSSIBLE" << endl;
  
    return 0;
}