a: found, num = 1 0:1
aa: found, num = 2 0:1 1:2
aaa: found, num = 2 0:1 1:2
ab: found, num = 2 0:1 2:2
abb: found, num = 2 0:1 2:2
abc: found, num = 3 0:1 2:2 4:3
abcd: found, num = 3 0:1 2:2 4:3
b: found, num = 1 6:1
ba: found, num = 1 6:1
bb: found, num = 1 6:1
c: found, num = 1 7:1
cd: found, num = 2 7:1 8:2
cddd: found, num = 2 7:1 8:2
ccd: found, num = 1 7:1
ddd: found, num = 1 9:3
eab: not found
