def f(*args):
    result = []
    for x in args[0]: 
        if x in result: 
            continue 
        for word in args[1:]: 
            if x not in word: 
                break 
        else: 
            result.append(x) 
    return ''.join(result)
s1, s2, s3= "message", "massage", "mask"
print(f(s1, s2, s3))

def f(*args):
    result = []
    for x in args[0]:  
        for word in args[1:]: 
            if x not in word: 
                break 
        else: 
            result.append(x) 
    return ''.join(result)
s1, s2, s3= "message", "massage", "mask"
print(f(s1, s2, s3))

def f(*args):
    res = ""
    l = len("".join(args[:-1]))
    for i, s in enumerate("".join(args)):
        if i > l:
            res += s
    return res
s1, s2, s3= "one", "two", "three"
print(f(s1, s2, s3))

def mineven(*args):
    res = args[0]
    for arg in args[1: ]:
        if arg < res and arg % 2 == 0:
            res = arg
    return res
data = [3, 2, 1, 0, -1, -2, -3]
mineven(*data)

def f(*args):
    result = []
    for seq in args:
        for x in seq:
            if not x in result:
                result.append(x)
    return ''.join(result)
s1, s2, s3= "message", "massage", "mask"
print(f(s1, s2, s3))

def f(*args):
    result = []
    for x in args[0]:
        for w in args[1:]:
            if x in w:
                break
        else:
            result.append(x)
    return "".join(result)

s1, s2, s3= "hello", "hi", "good morning"
print(f(s1, s2, s3))

sorted([1, 2, 3, 4, 5], key=lambda x: -x, reverse=True)

def f(arr):
    if not arr:
        return 0
    return arr[0] + f(arr[1:]) 
f([1, 2, 3, 4, 5])

def f(n):
    return n * f(n-1) if n > 1 else 1

def f(arr):
    return 0 if not arr else arr[0] + f(arr[1:])
print(f([]))