#include <iostream>
#include <fstream>
#include <algorithm>
#include <vector>
using namespace std;

ifstream fin("reguli.in");
ofstream fout("reguli.out");

int N;
vector < int64_t > V;
int L;

void Citire()
{
    int64_t X1,X2;
    fin>>N>>X1;
    V.resize(N+32);
    N--;
    for(int i=1; i<=N; i++)
    {
        X2=X1;
        fin>>X1;
        V[i]=X1-X2;
    }
}

void Rezolvare()
{
    for(auto x : V)
        cout<<x<<' ';
    int i,i2=1,sf=2;
    int i3;
    for(i=2; i<=N; i++)
    {
        if(i2>=sf)
            i2=i2%sf+1;
        if(V[i]==V[i2])
            i2++;
        else
        {
            i2=1;
            if(V[i]==V[1])
            {
                i3=i;
                while(i3>=sf && V[i3]==V[1])
                {
                    i3--;
                    i2++;
                }
                i3++;
                i2--;
                sf=i3+1;
            }
            else
                sf=i+1;
        }
    }
    L=sf;
}

void Afisare()
{
    fout<<L<<'\n';
    for(int i=1; i<=L; i++)
        fout<<V[i]<<'\n';
}

int main()
{
    Citire();
    Rezolvare();
    Afisare();
    return 0;
}