#include <bits/stdc++.h>
using namespace std;
template<class C>constexpr int sz(const C&c){return int(c.size());}
using ll=long long;constexpr const char nl='\n',sp=' ';
const int MAXN = 1e5 + 5;
int N, H[MAXN];
map<int, int> vals, diffs;
void add(int v) {
auto cur = vals.find(v);
if (cur != vals.end()) {
++cur->second;
++diffs[0];
return;
}
auto nxt = vals.upper_bound(v);
if (nxt != vals.begin() && nxt != vals.end()) {
auto it = diffs.find(nxt->first - prev(nxt)->first);
if (--it->second == 0) diffs.erase(it);
}
cur = vals.emplace_hint(nxt, v, 1);
if (nxt != vals.end()) ++diffs[nxt->first - v];
if (cur != vals.begin()) ++diffs[v - prev(cur)->first];
}
void rem(int v) {
auto cur = vals.find(v);
if (cur->second >= 2) {
--cur->second;
auto it = diffs.find(0);
if (--it->second == 0) diffs.erase(it);
return;
}
auto nxt = next(cur);
if (nxt != vals.end()) {
auto it = diffs.find(nxt->first - v);
if (--it->second == 0) diffs.erase(it);
}
if (cur != vals.begin()) {
auto it = diffs.find(v - prev(cur)->first);
if (--it->second == 0) diffs.erase(it);
}
vals.erase(cur);
if (nxt != vals.begin()) if (nxt != vals.end()) ++diffs[nxt->first - prev(nxt)->first];
}
bool check(int A, int B) {
int cur = A, diff = B - A;
vector<int> reinsert;
while (true) {
auto it = vals.lower_bound(cur);
if (it == vals.end() || it->first != cur) {
break;
}
reinsert.push_back(it->first);
rem(it->first);
cur += diff;
if (sz(diffs) <= 1) {
vector<int> A, B;
for (int v : reinsert) A.push_back(v);
for (auto &&p : vals) for (int i = 0; i < p.second; i++) B.push_back(p.first);
if (A.empty()) {
A.push_back(B.back());
B.pop_back();
}
if (B.empty()) {
B.push_back(A.back());
A.pop_back();
}
assert(sz(A) + sz(B) == N);
cout << sz(A) << nl;
for (int i = 0; i < sz(A); i++) cout << A[i] << " \n"[i == sz(A) - 1];
cout << sz(B) << nl;
for (int i = 0; i < sz(B); i++) cout << B[i] << " \n"[i == sz(B) - 1];
return true;
}
}
for (int v : reinsert) add(v);
return false;
}
int main() {
// freopen("in.txt", "r", stdin);
// freopen("out.txt", "w", stdout);
// freopen("err.txt", "w", stderr);
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> N;
for (int i = 0; i < N; i++) cin >> H[i];
sort(H, H + N);
for (int i = 0; i < N; i++) add(H[i]);
if (check(H[0], H[1])) return 0;
if (N >= 3 && check(H[0], H[2])) return 0;
if (N >= 3 && check(H[1], H[2])) return 0;
cout << -1 << nl;
return 0;
}
