# 1
nums = [
    [1, 2, 3],
    [4, 5, 6],
]
joined = sum(nums, [])
print(joined)

# 2
unique = [1, 2, 3, 3]
unique = list(set(unique))

# 3
# a = 10
# b = 20
a, b = 10, 20
a, b = b, a

# 4
total = [1, 2, 2, 2, 3, 3]
print(
    max(set(total), key=total.count)
)

# 5
print(*total, end='', sep='-')
print(*total, end='', sep='-')
