#include <stdio.h>

#define MAX_N 500005
#define FIN "reguli.in"
#define FOUT "reguli.out"

int N, pi[MAX_N]; 
long long X[MAX_N];
char buf[64], *p;

long long get(void)
{
    long long n = 0, sgn = +1;

    if (*p == '-') { sgn = -1; p++; }
    for (; *p >= '0' && *p <= '9'; p++)
        n = n*10 + *p-'0';
    return n*sgn;
}

int main(void)
{
    int i, j, r;

    freopen(FIN, "r", stdin);
    freopen(FOUT, "w", stdout);

    scanf("%d\n", &N);
    for (i = 0; i <= N; i++)
    {
        fgets(buf, sizeof(buf), stdin);
        p = buf;
        X[i] = get();
    }
    for (i = N; i > 0; i--)
        X[i] -= X[i-1];

    r = 0;    
    for (i = 2, j = pi[1] = 0; i <= N; i++)
    {
        for (; j > 0 && X[j+1] != X[i]; j = pi[j]);
        if (X[j+1] == X[i]) j++;
        pi[i] = j;

        if (pi[i] > 0 && i % (i-pi[i]) == 0) 
        {
            printf("%d\n", i-pi[i]);
            for (i = 1; i <= i-pi[i]; i++)
                printf("%lld\n", X[i]);
            return 0;
        }
    }

    return 0;
}