# Verbal arithmetic¶

A **verbal arithmetic** is a mathematical equation among unknown numbers, whose digits are represented by letters
(see wikipedia for more details).

## Input data¶

The equation we consider here is:

```
S E N D
+ M O R E
-----------
= M O N E Y
```

A value has to be assigned to each letter in such a way that the equation is satisfied. Note that:

- each letter corresponds to a digit,
- a word cannot start with à 0,
- no two letters are assigned to the same digit.