D = int(input())
coeff = list(map(int, input().split()))

b0 = 0
b1 = 0
b2 = 0

for i in range(D + 1):
    a_i = coeff[i]
    if i == 0:
        b0 += a_i
    elif i == 1:
        b1 += a_i
    elif i == 2:
        b2 += a_i
    else:
        if i % 2 == 1:  # 1 -> x^1
            b1 += a_i
        else:  # 0 -> x^2
            b2 += a_i

# Determine the maximum degree
max_deg = 0
coefficients = []
if b2 != 0:
    max_deg = 2
    coefficients = [b0, b1, b2]
elif b1 != 0:
    max_deg = 1
    coefficients = [b0, b1]
else:
    # Check if all are zero
    if b0 == 0:
        max_deg = 0
        coefficients = [0]
    else:
        max_deg = 0
        coefficients = [b0]

# Truncate coefficients list based on max_deg
if max_deg == 2:
    coefficients = coefficients[:3]  # [b0, b1, b2]
elif max_deg == 1:
    coefficients = coefficients[:2]  # [b0, b1]
else:
    coefficients = coefficients[:1]  # [b0]

# Now, check trailing zeros for higher degrees
# For example, if max_deg is 1 but b1 is zero due to previous steps
# But since max_deg is determined by checking non-zero, this should be handled

# Now handle the case where all are zero (but earlier handled by b0=0 -> coefficients [0])
# Now, output
print(max_deg)
print(' '.join(map(str, coefficients)))