//ojou kawayo no.1
#include <bits/stdc++.h>
using namespace std;
#define tsk "drvca"
#define pb push_back
#define pf push_front
//dm define endl
#define fi first
#define se second
#define Ningen_sama signed
#define tachi main()
#define __builtin_popcount __builtin_popcountll
#define el cout<<'\n'
#define all(a) a.begin(),a.end()
#define invAll(a) a.rbegin(),a.rend()
#define sz(a) ((int)a.size())
#define BIT(x, k) (1ll&(x >> k))
#define len(s) (int)s.size()
#define mem(a,x) memset(a,x,sizeof(a))
#define debug(x) cout << #x << " = " << x << '\n'
#define execute cerr << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << "s"
#define FOR(i, l, r) for(int i = (l), _r = (r); i <= _r; ++i)
#define FORD(i, l, r) for(int i = (l), _r = (r); i >= _r; --i)
#define REP(i, n) for(int i = 0, _n = (n); i < _n; ++i)
//#define int long long
template<class T> bool maximize(T& u, T v){if(u >= v) return false;return u = v, true;}
template<class T> bool minimize(T& u, T v){if(u <= v) return false;return u = v, true;}
using pii = pair<int, int>;
using ll = long long;
using vi = vector<int>;
using vpii = vector<pair<int, int>>;
#define inf32 0x3f3f3f3f
#define inf64 0x3f3f3f3f3f3f3f3f
const int maxn = 1e6+5;
const int N = 5e3 + 5;
const int base = 31;
const ll mod = 1e9 + 7;
const ll need = 67108863;
const int vc = 2e9 + 1;
const ll INF18 = 4557430888798830399;
const ll LOG = 20;
const double eps = 1e-9;
const int BLOCK = 447;
const int dx[4] = {1, 0, -1, 0};
const int dy[4] = {0, -1, 0, 1};
mt19937_64 rd(chrono::steady_clock::now().time_since_epoch().count());
#define rand rd
inline long long Rand(long long L, long long R) {
if(L>R) return 0;
return L + rd() % (R - L + 1);
}
inline ll add(ll x, ll y){x+=y;if(x>=mod) x-=mod;if(x<0) x+=mod;return x;}
inline ll mult(ll x, ll y){return 1LL * x * y % mod;}
int n;
int a[maxn];
inline void init(){
}
inline void input(){
cin >> n;
FOR(i, 1, n){
cin >> a[i];
}
}
inline void solve(){
vector<int> v1, v2;
sort(a + 1, a + 1 + n);
int diff;
bool check = true;
FOR(i, 2, n){
v1.clear();
v2.clear();
v1.push_back(a[1]);
v1.push_back(a[i]);
check = true;
diff = a[i] - a[1];
if(i != 2){
FOR(j, 2, i - 1){
v2.push_back(a[j]);
if(sz(v2) > 2 && v2[sz(v2) - 1] - v2[sz(v2) - 2] != v2[sz(v2) - 2] - v2[sz(v2) - 3]){
check = false;
break;
}
}
}
if(!check) continue;
// debug(i);
int posi = i, j = i + 1;
while(j <= n){
if(a[j] - a[posi] != diff){
// debug(j);
// debug(posi);
// debug(a[j]);
// debug(a[posi]);
// debug(diff);
// if(sz(v2)) cout << v2.back() << " ";
// if(sz(v2) > 1) cout << v2[sz(v2) - 2]; el;
v2.push_back(a[j]);
if(sz(v2) > 2 && v2[sz(v2) - 1] - v2[sz(v2) - 2] != v2[sz(v2) - 2] - v2[sz(v2) - 3]){
check = false;
break;
}
}
else{
posi = j;
v1.push_back(a[j]);
}
j++;
// if(!check) break;
}
// cout << sz(v1); el;
// for(int v : v1) cout << v << " "; el;
// cout << sz(v2); el;
// for(int v : v2) cout << v << " "; el;
// cout << check; el;
if(!check) continue;
if(sz(v1) + sz(v2) == n){
if(sz(v2) == 0){
v2.push_back(v1.back());
v1.pop_back();
}
cout << sz(v1); el;
for(int v : v1) cout << v << " "; el;
cout << sz(v2); el;
for(int v : v2) cout << v << " "; el;
return;
}
//el;
}
cout << -1;
}
Ningen_sama tachi{
//konnakiri~~
if(fopen(tsk".inp","r")){
freopen(tsk".inp","r",stdin);
freopen(tsk".out","w",stdout);
}
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
int Yodayo = 1;
//cin >> Yodayo;
//init();
while(Yodayo--){
input();
solve();
}
//execute;
}
//otsunakiri~~
