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**Task** | Statistics

Time limit: | 1.00 s | Memory limit: | 512 MB |

You are given a string. You can remove any number of characters from it, but you cannot change the order of the remaining characters.

How many different strings can you generate?

The first input line contains a string of size $n$. Each character is one of a–z.

Print one integer: the number of strings modulo $10^9+7$.

- $1 \le n \le 5 \cdot 10^5$

Input:

`aybabtu`

Output:

`103`