def div(a, b):
    if len(a) < len(b):
        return a
    
    count = len(a) - len(b) + 1
    for i in range(count):
        k = a[i] / b[0]
        for j in range(len(b)):
            a[i + j] = a[i + j] - k * b[j]
        print(a)
            
    rel = 0
    for l in range(len(a)):
        if a[l] != 0:
            rel = l
            break
    return a[l:]

        
d = int(input())
ary = list(map(int, input().split(' ')))

result = div(ary, [1, 0, -1, 0])


print(len(result) - 1)
for i in result:
    print(int(i), end=' ')
print()