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#include <cstdio>
using namespace std;

#define FOR(i,a,b) for(int i=(a);i<(b);++i)
#define REP(i,n) FOR(i,0,n)
#define INT(x) int x; scanf("%d", &x)

int main() {
	INT(n);
	int x = 2;
	REP(i,n) {
		INT(a);
		if (x && a == 1) --x;
	}
	printf("%d\n2\n1 2\n", x);
}