#include <stdio.h>
#include <string.h>
#define N 100000
unsigned int X = 12345;
int rand_() {
return (X *= 3) >> 1;
}
void sort(int *aa, int l, int r) {
while (l < r) {
int i = l, j = l, k = r, a = aa[l + rand_() % (r - l)], tmp;
while (j < k)
if (aa[j] == a)
j++;
else if (aa[j] < a) {
tmp = aa[i], aa[i] = aa[j], aa[j] = tmp;
i++, j++;
} else {
k--;
tmp = aa[j], aa[j] = aa[k], aa[k] = tmp;
}
sort(aa, l, i);
l = k;
}
}
int solve(int *aa, int n, int a, int b) {
static char in[N];
static int dd[N];
int i, k, c, d;
memset(in, 0, n * sizeof *in);
for (i = n - 2; i >= 0; i--)
dd[i] = i == n - 2 || dd[i + 1] == aa[i + 1] - aa[i] ? aa[i + 1] - aa[i] : -2;
k = 0, c = -1, d = -1;
for (i = 0; i < n; i++)
if (aa[i] == a) {
in[i] = 1, a += b, k++;
if (k < n) {
if (i == n - 2) {
if (c != -1 && d != -1 && aa[i + 1] - c != d)
continue;
} else if (i < n - 2) {
if (dd[i + 1] == -2)
continue;
if (d != -1 && d != dd[i + 1])
continue;
if (c != -1 && aa[i + 1] - c != dd[i + 1])
continue;
}
printf("%d\n", k);
for (i = 0; i < n; i++)
if (in[i])
printf("%d ", aa[i]);
printf("\n");
printf("%d\n", n - k);
for (i = 0; i < n; i++)
if (!in[i])
printf("%d ", aa[i]);
printf("\n");
return 1;
}
} else {
if (c != -1) {
if (d != -1 && aa[i] - c != d)
return 0;
d = aa[i] - c;
}
c = aa[i];
}
return 0;
}
int main() {
static int aa[N];
int n, i;
scanf("%d", &n);
for (i = 0; i < n; i++)
scanf("%d", &aa[i]);
sort(aa, 0, n);
if (!solve(aa, n, aa[0], aa[1] - aa[0]) && !solve(aa, n, aa[0], aa[2] - aa[0]) && !solve(aa, n, aa[1], aa[2] - aa[1])) {
printf("-1\n");
return 0;
}
return 0;
}
