p02682 AtCoder Beginner Contest 167 - Easy Linear Programming
We have A cards, each of which has an integer 1 written on it. Similarly, we also have B cards with 0s and C cards with -1s.

We will pick up K among these cards. What is the maximum possible sum of the numbers written on the cards chosen?

Constraints

* All values in input are integers.
* 0 \leq A, B, C
* 1 \leq K \leq A + B + C \leq 2 \times 10^9

Input

Input is given from Standard Input in the following format:


A B C K


Output

Print the maximum possible sum of the numbers written on the cards chosen.

Examples

Input

2 1 1 3


Output

2


Input

1 2 3 4


Output

0


Input

2000000000 0 0 2000000000


Output

2000000000
```python
A, B, C, K = map(int, input().split())

hoge = max(K - A - B, 0)

print(min(A, K) - hoge)

```