1
 2
 3
 4
 5
 6
 7
 8
 9
10
11
12
13
14
15
16
17
18
19
// eeeee?
#include <cstdio>
#include <algorithm>

using namespace std;

int main() {
       int ones = 0;
       int n;
       int tmp;
       scanf("%d", &n);
       for (int i = 0 ; i < n; i++) {
	       scanf("%d", &tmp);
	       if (tmp == 1)
		       ones++;
       }

       printf("%d\n2\n1 2\n", max(0, 2 - ones));
}