#include <bits/stdc++.h>
using namespace std;
#define int long long
#define yes cout << "YES\n";
#define no cout << "NO\n";
void FastIO(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cout.tie(nullptr);
}
///Sum of two values
void solve(){
int n,x; cin >> n >> x;
vector<int>vec(n+1);
map<int,pair<int,int>> freq;
for(int i = 1; i <= n; i++){
cin >> vec[i];
}
int l,r; bool flg = false;
for(int i = 1; i <= n; i++){
if(freq[x-vec[i]].second > 0){
flg = true;
l = freq[x-vec[i]].first;
r = i;
break;
}
freq[vec[i]].first = i;
freq[vec[i]].second++;
}
if(flg){
cout << l << " " << r;
}
else{
cout << "IMPOSSIBLE";
}
}
signed main(){
FastIO();
int t = 1;
//cin >> t;
while(t--){
solve();
}
return 0;
}
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