#include <bits/stdc++.h>
using namespace std;
#define fastIO ios_base::sync_with_stdio(false), cin.tie(NULL);
#define PI acos(-1.0)
#define eps 1e-9
#define FF first
#define SS second
// VECTOR (6)
#define pb push_back
#define lb lower_bound
#define ub upper_bound
#define sz(v) int((v).size())
#define all(v) (v).begin(), (v).end()
#define uniq(v) sort(all( (v) )), (v).resize( unique(all( (v) )) - (v).begin() );
// BIT (6)
#define CNTBIT(x) __builtin_popcountll(x)
#define ODDBIT(x) __builtin_parityll(x)
#define MASK(i) (1LL<<(i))
#define BIT(x, i) (((x)>>(i))&1)
#define SUBSET(big, small) (((big)&(small))==(small))
#define MINBIT(x) (x)&(-x)
#define FIRSTBIT(x) __builtin_ctzll(x)
//typedef
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<ll, int> ii;
/* */
template<class T>
bool minimize(T &a, const T &b) {
if(a > b) {a = b; return 1;}
return 0;
}
template<class T>
bool maximize(T &a, const T &b) {
if(a < b) {a = b; return 1;}
return 0;
}
/* */
/* CODE BELOW */
const int N = 1e5 + 7, M = 1e9 + 7;
const int oo = 1e16 + 7;
const int MOD = 1e9 + 7;
int n;
int a[N];
void print(const vector<int> &A, const set<int> &B) {
printf("%d\n", sz(A));
for(int v:A) printf("%d ", v);
printf("\n%d\n", sz(B));
for(int v:B) printf("%d ", v);
exit(0);
}
void solve(int first, int second) {
vector<int> A; set<int> B, diffB;
for(int i=1;i<=n;i++) B.insert(a[i]);
A.pb(first), A.pb(second);
B.erase(B.find(first));
B.erase(B.find(second));
int prv = -1, diff = second - first;
for(int v:B) {
if(prv != -1) diffB.insert(v - prv);
prv = v;
}
prv = second + diff;
for(;sz(A) < n;prv+= diff) {
if(*diffB.begin() == *diffB.rbegin()) {
print(A, B);
}
auto it = B.find(prv);
if(it == B.end()) break;
auto L = it, R = it;
if(it != B.begin()) {
L--; diffB.erase(diffB.find(*it - *L));
}
if(it != B.end()) {
R++; diffB.erase(diffB.find(*R - *it));
if(it != B.begin()) {
diffB.insert(*R - *L);
}
}
A.pb(prv); B.erase(B.find(prv));
}
}
signed main() {
//freopen("test.inp", "r", stdin);
//freopen("test.out", "w", stdout);
//fastIO;
scanf("%d", &n);
for(int i=1;i<=n;i++) scanf("%d", &a[i]);
sort(a+1, a+n+1);
solve(a[1], a[2]);
solve(a[1], a[3]);
solve(a[2], a[3]);
printf("-1");
return 0;
}
