#include <iostream>
#include <fstream>
#define Nmax 500005
using namespace std;
ifstream fin("reguli.in");
ofstream fout("reguli.out");
int pi[Nmax];
int main()
{
    int n,x0,a[Nmax],x,i;
    fin>>n;
    --n;
    fin>>x0;
    for(i=0;i<n;++i)
    {
        fin>>x;
        a[i]=x-x0;
        x0=x;
    }
    int k=0;
    for(i=2;i<=n;++i)
    {
        while(k && a[i-1]!=a[k])k=pi[k];
        if(a[i-1]==a[k])++k;
        pi[i]=k;
    }
    int current = pi[n]-1;
    for(i=n-1;i>=1;--i)
    {if(pi[i]!=current)break;
    --current;
    }
    int numar=i+1;
    if(numar <= n/2)
    {   fout<<numar<<'\n';
        for(i=0;i<numar;++i)
            fout<<a[i]<<'\n';
    }
    else
    {
        fout<<n<<'\n';
        for(i=0;i<n;++i)
            fout<<a[i]<<'\n';
    }

    return 0;
}