1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
20
21
22
#include <bits/stdc++.h>
#define FOR(i, a, b) for (int i=(a); (i)<(b); (i)++)
#define PPC(x) __builtin_popcountll((x))
#define ALL(x) (x).begin(), (x).end()
#define pb push_back
using namespace std;

int main()
{
	int n, ones = 0;
	scanf ("%d", &n);
	while (n--)
	{
		int a;
		scanf ("%d", &a);
		if (a == 1)
			ones++;
	}
	ones = min(ones, 2);
	printf("%d\n2\n1 2\n", 2 - ones);
	return 0;
}