Count the number of integer solutions to the following equation:
$$x_1 + x_2 + ... + x_k = n$$
with $x_i \ge p$.
### Input
- A single line contains 3 integers $n, k, p$.
### Output
- Print the number of solutions, modulo $10^9+7$.
### Constraints
- $1 \le n, k, p \le 10^6$.
### Example
Input:
```
8 3 1
```
Output:
```
21
```
