s = 'arefhjaref!!'
out = []
max_len = 0
for i in range(len(s)):
    t = s[i:]
    for j in range(len(t),1,-1):
        s1,s2 = t[:j],t[j:]
        if s2.find(s1) < 0: continue
        if len(s1) < max_len: continue
        max_len = len(s1)
        out.append(s1)
out.sort(key = lambda x: len(x),reverse=True)
print(out)

 s = 'ntarefhjaref!!bvfhjarefantarefh'
 
def long_substr():
    n = len(s)//2
    b = True
    while b:
        for i in range(len(s) - n*2 +1):
            if s[i:i+n] in s[i+n:]:
                yield s[i:i+n]
                b = False
        if n < 2:
            return
        n -= 1
 
print('long_substr =', list(long_substr()))