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

Arthur took a group of four integers a,b,w,x (0≤b<w,0<x<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≥x, perform the assignment b=b-x, if b<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≤a.

The first line contains integers a,b,w,x,c (1≤a≤2·10⁹,1≤w≤1000,0≤b<w,0<x<w,1≤c≤2·10⁹).

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.