Arthur and Alexander are number busters. Today they've got a competition.

Arthur took a group of four integers a,b,w,x (0 \le b \lt w,0 \lt x \lt w) and Alexander took integer c. Arthur and Alexander use distinct approaches to number bustings. Alexander is just a regular guy. Each second, he subtracts one from his number. In other words, he performs the assignment: c=c-1. Arthur is a sophisticated guy. Each second Arthur performs a complex operation, described as follows: if b \ge x, perform the assignment b=b-x, if b \lt x, then perform two consecutive assignments a=a-1;b=w-(x-b).

You've got numbers a,b,w,x,c. Determine when Alexander gets ahead of Arthur if both guys start performing the operations at the same time. Assume that Alexander got ahead of Arthur if c \le a.

The first line contains integers a,b,w,x,c (1 \le a \le 2 \cdot 109,1 \le w \le 1000,0 \le b \lt w,0 \lt x \lt w,1 \le c \le 2 \cdot 109).

Print a single integer - the minimum time in seconds Alexander needs to get ahead of Arthur. You can prove that the described situation always occurs within the problem's limits.