#include <bits/stdc++.h>
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 i = 0, j = n - 1;

  while(i < j) {
    if(niza[i].first + niza[j].first == x) {
      cout << niza[i].second + 1 << " " << niza[j].second + 1 << endl;
      return 0;
    }
    if(niza[i].first + niza[j].first < x) {
      i++;
    }
    else {
      j--;
    }
  }


  cout << "IMPOSSIBLE" << endl;
  return 0;
}