#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 + 1;
   }
   sort(niza, niza + n);
   int i = 0;
   int j = n - 1;
   while(i < j){
       int sum = niza[i].first + niza[j].first;
       if(sum == x){
           cout << niza[i].second << " " << niza[j].second;
           return 0;
       }
       else if(sum < x){
           i++;
       }
       else{
           j--;
       }
   }
   cout << "IMPOSSIBLE";
   return 0;