#include <bits/stdc++.h>
#define REP(i,a,b) for (auto i = (a); i <= (b); ++i)
#define PER(i,a,b) for (auto i = (b); i >= (a); --i)
#define log2(x) (31-__builtin_clz(x))
#define ALL(x) (x).begin(), (x).end()
#define RALL(x) (x).rbegin(), (x).rend()
#define SZ(x) (int)(x).size()
#define PB push_back
#define FI first
#define SE second
#define mup(x,y) x = min(x,y)
#define Mup(x,y) x = max(x,y)
#define debug(x) cout << #x << " is " << x << el
#define el '\n'
using namespace std; using ll = long long; using ii = pair<int,int>; using iii = tuple<int,int,int>;
void solution(); int main() {ios::sync_with_stdio(0); cin.tie(0); solution();}
const int N = 100003;
int n, h[N];
bool isA[N];
void print() {
vector<int> a, b;
REP(i, 1, n) {
if (isA[i])
a.push_back(h[i]);
else
b.push_back(h[i]);
}
cout << SZ(a) << el;
for (auto p : a)
cout << p << ' ';
cout << el << SZ(b) << el;
for (auto p : b)
cout << p << ' ';
}
void input() {
cin >> n;
REP(i,1,n) cin >> h[i];
}
void solution() {
input();
sort(h+1,h+n+1);
bool chk;
//first, A: h[1], h[3],...
isA[1] = true; chk = true;
for (int preA = h[1], rA = h[3]-h[1], i = 3; i <= n; ++i) {
if (h[i] == preA+rA) {
isA[i] = true;
preA += rA;
}
} int preB = h[2], rB = 1000000; REP(i,4,n) {
if (!isA[i]) {
rB = h[i]-preB;
break;
}
} REP(i,4,n) {
if (!isA[i]) {
if (h[i] != preB+rB) {chk = false; break;}
preB += rB;
}
}
if (chk) {print(); return;}
//second, A: h[1], h[2],...
fill(isA,isA+n+1,0);
isA[1] = true; chk = true;
for (int preA = h[1], rA = h[2]-h[1], i = 2; i <= n; ++i) {
if (h[i] == preA+rA) {
isA[i] = true;
preA += rA;
}
} preB = 0, rB = 1000000; int i;
for(i = 1; i <= n; ++i) if (!isA[i]) {preB = h[i]; break;}
for (++i; i <= n; ++i) if (!isA[i]) {rB = h[i]-preB; break;}
for (; i <= n; ++i) {
if (!isA[i]) {
if (h[i] != preB+rB) {chk = false; break;}
preB += rB;
}
}
if (chk) {print(); return;}
cout << -1;
}
