s ="gigKKDKDMTsigj40jsjh-jfkmnsiofsmnlmbpdsldgmdgddggdkokokokkkkkklllleekgeg"

def func(s, f=''):
    x = ''
    y = ''
    if f == 'longest':
        for i, elem in enumerate(s):
            if i == 0:
               x = elem
               continue
            if elem.lower() in x or elem in x:
                x += elem
            else:
                if len(x) > len(y):
                    y = x
                x = elem
        return y

    elif f == 'alphanumerically_last':
        for i, elem in enumerate(s):
            if i == 0:
                x = elem.lower()
                continue
            if elem.isalpha() and ord(elem.lower()) > ord(x):
                x = elem.lower()

        return x

    elif f =='same_vowels':
        for i, elem in enumerate(s):
            if i == 0:
                continue
            if elem.lower() in 'aueoyiаеуоияюэ' and elem == s[i - 1]:
                return True

        return False

print(func(s, 'longest'))
print(func(s, 'same_vowels'))
print(func(s, 'alphanumerically_last'))