#include <bits/stdc++.h>
using namespace std;
#define int long long
const int maxn = 1e5 + 5;
int n, p[maxn];
void check(int a, int b){
multiset<int> s, diff;
for(int i = 0; i < n; i++) s.insert(p[i]);
s.erase(s.find(a));
s.erase(s.find(b));
vector<int> ans;
ans.push_back(a);
ans.push_back(b);
int last = -1;
for(auto x: s){
if(last != -1) diff.insert(x - last);
last = x;
}
int k = b - a;
int tmp = b + k;
do{
if(*diff.begin() == *diff.rbegin()){
cout << ans.size() << "\n";
for(int x: ans) cout << x << " ";
cout << "\n" << s.size() << "\n";
for(int x: s) cout << x << " ";
exit(0);
}
auto it = s.find(tmp);
if (it == s.end()) break;
auto l = it, r = it;
if(it != s.begin()) {
l--;
diff.erase(diff.find(*it - *l));
}
r++;
if(r != s.end()){
diff.erase(diff.find(*r - *it));
if (it != s.begin()) diff.insert(*r - *l);
}
s.erase(it);
ans.push_back(tmp);
tmp += k;
} while((int)ans.size() < n);
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(0); cout.tie(0);
cin >> n;
for(int i = 0; i < n; i++) cin >> p[i];
sort(p, p + n);
if(n <= 4){
cout << n / 2 << "\n";
for(int i = 0; i < n / 2; i++) cout << p[i] << " ";
cout << "\n" << n - n / 2 << "\n";
for(int i = n / 2; i < n; i++) cout << p[i] << " ";
}else{
check(p[0], p[1]);
check(p[0], p[2]);
check(p[1], p[2]);
cout << -1;
}
}
