Kids always like imitate other people what they say. Although it maybe not correct.
But it does not matter, because kids don’t spell all letters at the beginning.
Now kids are learning speak words, and he or she will follow what father says.
Father should check if it is a subsequence of a string what kids say that father just says.
For example, "ace" is a subsequence of "adcbe" but not a subsequence of "bcae".
If he spell correctly, father will tell him "YES", otherwise "NO".
But I want to make it mysterious, so I will only tell you the first character of father's words and kid's words,
you should know it only by follows:
s0 = first character;
si = char((pos(S(i-1)) * multiplier + i * adder) % 26);
pos(a) = 0, pos(b) = 1, ....pos(z) = 25;
char(0)= a, char(1)= b, .....char(25)= z;