# Pre-condition: s is a string of lowercase letters only.
def whatdoesitdo(s):

    n = len(s)

    # Works like an array but we can index with anything.
    chart = {}
    sz = 0
    
    for i in range(n-1):

        # Grabs a substring of s starting at index i of length 2.
        tmp = s[i:i+2]

        # Checks if our "array" has an entry for tmp.
        if tmp in chart:
            chart[tmp] += 1
        else:
            chart[tmp] = 1

        sz = max(sz, chart[tmp])

    # Creates sz+1 lists.
    res = []
    for i in range(sz+1):
        res.append([])

    for tmp in chart:
        res[chart[tmp]].append(tmp)

    # Sorts each list in alphabetical order.
    for i in range(sz+1):
        if len(res[i]) > 0:
            res[i].sort()

    return res

def main():

    inp = input().strip()

    res = whatdoesitdo(inp)

    # Loops from length of res downto 2.
    for i in range(len(res)-1,1,-1):

        print(i)
        print("--------")
        for x in res[i]:
            print(x)
        print()

main()