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#include <bits/stdc++.h>
using namespace std;

const int MAXN = 1000000;

int a, n, C[MAXN];

int main()
{
    scanf("%d", &n);
    for (int i = 0; i < n; ++i) {
        scanf("%d", &a);
        ++C[a];
    }
    cout << max(2 - C[1], 0) << "\n2\n1 2\n";
    return 0;
}