#include <bits/stdc++.h>
#define REP(i,n,N) for(int i=(n);i<(int) N;i++)
using namespace std;

int main(void){
	int d;
    cin >> d;
    vector<int> b(d + 1);
    REP(i,0, d + 1) cin >> b[i];
    reverse(b.begin(),b.end());
    REP(i,0, d - 2){
        b[i + 2] += b[i];
    }
    if(b[d - 2] != 0 && d - 2 >= 0){
        printf("2\n");
        printf("%d %d %d\n", b[d], b[d - 1], b[d - 2]);
    }else if(b[d - 1] != 0 && d - 1 >= 0){
        printf("1\n");
        printf("%d %d\n", b[d], b[d - 1]);
    }else{
        printf("0\n");
        printf("%d\n", b[d]);
    }
    return 0;
}