Given four positive integers $S,n,L,H$. Count the number of integer solutions of the following equation:
$$x_1+x_2+...+x_n=S$$
that satisfy:
$$L \le x_i \le H$$ for all $i$ such that $(1 \le i \le n)$
### Input
- Consists of four integers $S,n,L,H$ $(0 \le L \le H \le S,1 \le n \le S \le 10^6)$ .
### Output
- Print the answer modulo $10^9+7$.
### Và dụ
Input:
```
5 3 0 2
```
Output:
```
3
```
