#include <cstdio>
#include <algorithm>
#include <cstring>
#define Nmax 500002
using namespace std;
int n, i, j, p[Nmax];
long long v[Nmax];
void read()
{
    long long a, b;
    scanf("%d", &n);
    scanf("%lld", &a);
    for (i = 1; i < n; ++ i)
        scanf("%lld", &b),
              v[i] = b - a,
                     a = b;
}
void prefix()
{
    int k = 0,q;
    p[1] = 0;
    for (q = 2; q < n; ++ q)
    {
        while (k > 0 && v[k + 1] != v[q])
            k = p[k];
        if (v[k + 1] == v[q])
            ++ k;
        p[q] = k;
    }
}
void write()
{
    printf("%d\n", n - p[n - 1] - 1);
    for (int i = 1; i < n - p[n - 1]; ++ i)
        printf("%lld\n", v[i]);
}
int main()
{
    freopen("reguli.in", "r", stdin);
    freopen("reguli.out", "w", stdout);
    read();
    prefix();
    write();
    return 0;
}