#include <fstream>
#define DIM 500000
using namespace std;
ifstream fin("reguli.in");
ofstream fout("reguli.out");
int n,x,y,v[DIM],p[DIM];
int main() {
    fin>>n>>x;
    n--;
    for (int i=1;i<=n;i++) {
        fin>>y;
        v[i]=y-x;
        x=y;
    }
    p[1]=0;
    int j=0;
    for (int i=2;i<=n;i++) {
        while (j!=0 && v[i]!=v[j+1])
            j=p[j];
        if (v[i]==v[j+1])
            j++;
        p[i]=j;
    }
    fout<<n-p[n]<<"\n";
    for (int i=1;i<=n-p[n];i++)
        fout<<v[i]<<"\n";
    return 0;
}