#include <fstream>

using namespace std;

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

typedef long long ll;

const int N=500000+5;

int n;
ll v[N];
int ps[N];

inline void build_ps()
{
    int i=1;
    int cur=0;
    while(i<n)
    {
        if(v[i]==v[cur])
        {
            cur++;
            ps[i]=cur;
            i++;
        }
        else
        {
            if(cur==0)
            {
                i++;
            }
            else
            {
                cur=ps[cur-1];
            }
        }
    }
}

int main()
{
    fin>>n;
    ll l;
    fin>>l;
    for(int i=0;i+1<n;i++)
    {
        ll x;
        fin>>x;
        v[i]=x-l;
        l=x;
    }
    n--;
    build_ps();
    int ans=n-ps[n-1];
    fout<<ans<<"\n";
    for(int i=0;i<ans;i++)
    {
        fout<<v[i]<<"\n";
    }
    return 0;
}