Ositus

# I="aybabtu"+"ghsdfgljkaseifsdccfgsfbdvkfsdffdgfbdruffvrvfnvfsfdgefaslnghfo"
#555929291
I=input()
ends=[1]
cut=0
minimum=0
oldmin=0
for i in range(1,len(I)):
    s=I[i]
    cut=I.rfind(s,0,i)
    if minimum<cut+1:
        minimum=cut+1
    # ends.keys() == range(oldmin,i)
    # range(minimum,i) == ends.keys() & k>cut
    # newEnds.keys() == range(minimum,i+1)
    # len(ends) == i-oldmin
    # len(newEnds) == i-minimum+1

    # newEnds=[]
    # for k in range(i-minimum):
    #     # ends.keys() & k>cut
    #     newEnds.append(ends[k+minimum-oldmin])
    newEnds = ends[minimum-oldmin:]
    # t=0
    # for k in range(len(ends)):
    #     t+=ends[k]%(7+(10**9))
    t=sum(ends)%(7+(10**9))
    newEnds.append(t)

    ends=newEnds
    oldmin=minimum
    # print(cut)
    # print(ends)



# total=0
# # for k in range(len(ends)):
# #     total+=ends[k]
# for k in ends:
#     total+=k
total = sum(ends)
print(total%(7+(10**9)))

Test 1

Group: 1, 2, 3

Verdict: ACCEPTED

Test 2

Group: 1, 2, 3

Verdict: ACCEPTED

Test 3

Group: 1, 2, 3

Verdict: ACCEPTED

Test 4

Group: 1, 2, 3

Verdict: ACCEPTED

Test 5

Group: 2, 3

Verdict: ACCEPTED

Test 6

Group: 3

Verdict: ACCEPTED

Test 7

Group: 3

Verdict: TIME LIMIT EXCEEDED