Sum of Two Values

                                #include<bits/stdc++.h>
using namespace std;
#define INF 2147483647
#define INFL 9223372036854775807
#define pii pair<int,int>
#define F first
#define S second
#define mp make_pair
#define pb push_back
#define ll long long
#define ull unsigned long long
#define M 1000000007
#define FASTIO ios_base::sync_with_stdio(false);cin.tie(NULL); cout.tie(NULL);
#define take(x) scanf("%d",&x)
#define DE(x) printf("\ndebug %d\n",x);
#define vout(x) for(int i=0;i<x.size();i++) printf("%d ",x[i]);
#define pie acos(-1)
#define MOD 998244353

int main(){
    FASTIO;
    int n,x;
    cin>>n>>x;
    int ara[n];
    pii para[n];
    for(int i=0;i<n;i++){
        cin>>ara[i];
        para[i] =mp(ara[i],i+1);
    }

    sort(ara,ara+n);
    sort(para,para+n);
    for(int i=0;i<n;i++){
        if( binary_search(ara+i+1,ara+n,x-ara[i]) ){
            cout<<para[i].S<<" "<<para[lower_bound(ara+i+1,ara+n,x-ara[i])-ara].S;
            return 0;
        }

    }
    printf("IMPOSSIBLE");
}