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#include <bits/stdc++.h>
using namespace std;
#define FOR(i, n) for (int i = 0; i < n; i++)
#define FORR(i, n) for (int i = 1; i <= n; i++)
#define FORi(n) for (int i = 0; i < n; i++)
int main()
{
   ios_base::sync_with_stdio(false);
   cin.tie(NULL);
   int n;
   cin >> n;
   int licz = 0;
   for (int i = 0; i < n; i++)
   {
      int x;
      cin >> x;
      if (x == 1)
         licz++;
   }
   if (licz == 0)
      cout << "2\n";
   if (licz == 1)
      cout << "1\n";
   if (licz > 1 )
      cout << "0\n";
    
   cout << "2\n1 2";
   return 0;
}