Problem Statement

In front of idsigma, there are $A$ vegetables and $B$ pieces of meat. He is not fond of vegetables, but for the sake of his health, he is trying to eat at least a few vegetables today.
In order for idsigma to eat a certain number of vegetables, he must at the same time eat $C$ times that number of pieces of meat. However, idsigma can eat at most $D$ items in total, counting vegetables and meat together, today. What is the maximum number of vegetables idsigma can eat today?

Input

$A\ B\ C\ D$

$1\le A,B,C,D\le 100$

Output

Output one integer representing the maximum number of vegetables idsigma can eat. Print a newline at the end.

Sample

3 8 4 12

2

3 8 100 12

0