#pragma GCC optimize("O1,O2,O3,Ofast,unroll-loops")
#include <bits/stdc++.h>
#include <string>
#include <iostream>
#include <cmath>
#include <numeric>
#include <stack>
#include <queue>
#include <set>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pi;
typedef pair<ll, ll> pl;
typedef pair<ld, ld> pd;
typedef vector<int> vi;
typedef vector<bool> vb;
typedef vector<vector<int>> vvi;
typedef vector<vector<pi>> vvpi;
typedef vector<ld> vd;
typedef vector<long long> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
#define FOR(i, a, b) for (ll i = a; i < (b); i++)
#define F0R(i, a) for (int i = 0; i < (a); i++)
#define FORd(i, a, b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i, a) for (int i = (a)-1; i >= 0; i--)
#define trav(a, x) for (auto &a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
#define len(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define F first
#define nl endl
#define S second
#define lb lower_bound
#define ub upper_bound
#define aint(x) x.begin(), x.end()
#define raint(x) x.rbegin(), x.rend()
#define ins insert
const int M = 1e9+7;
void init(string name)
{
freopen((name + ".in").c_str(), "r", stdin);
freopen((name + ".out").c_str(), "w", stdout);
}
void fastIO()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
}
void solve()
{
int n;cin >> n;
vi arr(n);
FOR(i,0,n)cin >> arr[i];
sort(arr.begin(),arr.end());
FOR(k,0,3){
FOR(i,k+1,3){
int d = arr[i] - arr[k];
int cnt = 2;
multiset<int> arr2;
FOR(j,0,n){
if(i==j)continue;
if(k==j)continue;
arr2.insert(arr[j]);
}
vi arr3 = {arr[i],arr[k]};
cerr << arr[i] << " " << arr[k] << " " << d << endl;
while(arr2.count(arr[0]+(d*cnt))){
arr3.pb(arr[0]+d*cnt);
arr2.erase(arr2.find(arr[0]+d*cnt));
cnt ++;
}
cerr << "arr3 -> ";
for(int a:arr3)cerr << a << " ";
cerr << endl;
vi arr4;
for(int a:arr2)arr4.pb(a);
if(arr3.size() == n){
arr4.pb(arr3[0]);
arr3.erase(arr3.begin());
}else{
cerr << "arr4 -> ";
for(int a:arr4)cerr << a << " ";
cerr << endl;
d = arr4[1] - arr4[0];
cnt = 1;
while(cnt < arr4.size() && (arr4[cnt] - arr4[cnt-1]) == d){
cnt ++;
}
cerr << cnt << " " << arr4.size() << endl;
cerr << endl;
if(arr4.size() != 1 && cnt != arr4.size())continue;
}
if(arr3.size() + arr4.size() == n){
sort(arr3.begin(),arr3.end());
sort(arr4.begin(),arr4.end());
cout << arr3.size() << endl;
for(int a:arr3)cout << a << " ";
cout << endl;
cout << arr4.size() << endl;
for(int a:arr4)cout << a << " ";
cout << endl;
return;
}
}
}
cout << -1 << endl;
}
int main()
{
fastIO();
// init("test");
int t = 1;
// cin >> t;
while (t--)
solve();
return 0;
}
