#include <cstdio>
#define nmax 500005

using namespace std;

int v[nmax], nxt[nmax];
int x, y, i, n, q;

int main()
{
    freopen("reguli.in", "rt", stdin);
    freopen("reguli.out", "wt", stdout);

    scanf("%d", &n);
    scanf("%d", &x);

    for(i=1; i<=n; ++i)
    {
        scanf("%d", &y);
        v[i]=x-y;
        x=y;
    }
    --n;
    q=0;
    for(i=2; i<=n; ++i)
    {
        while(q && v[i]!=v[q+1]) q=nxt[q];

        if(v[i]==v[q+1]) ++q;

        nxt[i]=q;
    }

    int qq=n-nxt[n];
    printf("%d\n", qq);

    for(i=1; i<=qq; ++i)
    printf("%d\n", v[i]);

    return 0;
}