#include <fstream>
#include <iostream>

using namespace std;

#define int long long

ifstream in("reguli.in");
ofstream out("reguli.out");
int n;
int v[500005];
int dif[500005];
int lps[500005];

void build_lps()
{
    int i = 1;
    int j = 0;

    while(i < n)
    {
        if(dif[i] == dif[j])
        {
            j++;
            lps[i] = j;
            i++;
        }
        else
        {
            if(j == 0)
            {
                i++;
            }
            else
            {
                j = lps[j - 1];
            }
        }
    }
}

signed main()
{
    in>>n;
    for(int i = 1; i<=n; i++)
    {
        in>>v[i];

        if(i >= 2)
        {
            dif[i - 2] = v[i] - v[i - 1];
        }
    }
    n--;

    build_lps();

    int len = n - lps[n - 1];
    out<<len<<'\n';

    for(int i = 0; i<len; i++)
    {
        out<<dif[i]<<'\n';
    }

    return 0;
}