In a mystical land of letters, there lived a scribe who possessed a long string of magical symbols called s.

The scribe had a secret target spell, t, that needed to be formed from s.

The magic scrolls had a simple rule:

• You can remove symbols from s, but you cannot rearrange them.

• The symbols you keep, in order, form a subsequence.

Your task as the apprentice is to:

Count how many distinct ways the scribe can select symbols from s to exactly form the spell t.