#include <bits/stdc++.h>
#define endl '\n'
using namespace std;
using lint = long long;
const int maxn = 2e5 + 5;
const int inf = 1e9 + 5;
const int mod = 1e9 + 7;
int n;
int a[maxn];
multiset<int> s1;
multiset<int> s2;
multiset<int> sd;
void print() {
cout << s1.size() << endl;
while(!s1.empty()) {
cout << *s1.begin() << " ";
s1.erase(s1.begin());
}
cout << endl;
cout << s2.size() << endl;
while(!s2.empty()) {
cout << *s2.begin() << " ";
s2.erase(s2.begin());
}
}
bool trav(int i, int j) {
s1.clear();
s2.clear();
sd.clear();
for(int pos = 0; pos < n; pos++) {
if(pos > 0 && pos != i && pos - 1 != i)
sd.insert(a[pos] - a[pos - 1]);
else if(pos > 1 && pos != i && pos - 1 == i)
sd.insert(a[pos] - a[pos - 2]);
if(pos == i)
s1.insert(a[pos]);
else
s2.insert(a[pos]);
}
int d = a[j] - a[i];
for(int k = 2, curr; k <= n; k++) {
curr = a[i] + (k - 1) * d;
auto it = s2.find(curr);
if(it == s2.end())
return false;
int prv = 0, nxt = 0;
if(it != s2.begin()) {
prv = *prev(it);
sd.erase(sd.find(curr - prv));
}
it++;
if(it != s2.end()) {
nxt = *it;
sd.erase(sd.find(nxt - curr));
}
it--;
if(prv && nxt)
sd.insert(nxt - prv);
s2.erase(it);
s1.insert(curr);
if(*sd.begin() == *sd.rbegin())
return true;
}
return false;
}
signed main() {
#ifdef Local
freopen("in.txt", "r", stdin);
freopen("out.txt", "w", stdout);
#endif
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n;
for(int i = 0; i < n; i++)
cin >> a[i];
sort(a, a + n);
if(n == 2) {
cout << 1 << endl << a[0] << endl;
cout << 1 << endl << a[1] << endl;
return 0;
}
if(n == 3) {
cout << 1 << endl << a[0] << endl;
cout << 2 << endl << a[1] << " " << a[2] << endl;
return 0;
}
if(trav(0, 1)) {
print();
return 0;
}
if(trav(0, 2)) {
print();
return 0;
}
if(trav(1, 2)) {
print();
return 0;
}
cout << -1 << endl;
}
