ELEVTRBL - Elevator Trouble

You are on your way to your first job interview as a program tester, and you are already late. The interview is in a skyscraper and you are currently in floor s, where you see an elevator. Upon entering the elevator, you learn that it has only two buttons, marked "UP u" and "DOWN d". You conclude that the UP-button takes the elevator u floors up (if there aren't enough floors, pressing the UP-button does nothing, or at least so you assume), whereas the DOWN-button takes you d stories down (or none if there aren't enough). Knowing that the interview is at floor g, and that there are only f floors in the building, you quickly decide to write a program that gives you the amount of button pushes you need to perform. If you simply cannot reach the correct floor, your program halts with the message "use the stairs".

Given input f, s, g, u and d (floors, start, goal, up, down), find the shortest sequence of button presses you must press in order to get from s to g, given a building of floors, or output "use the stairs" if you cannot get from s to g by the given elevator.

Input

The input will consist of one line, namely f s g u d, where 1 <= s, g <= f <= 1000000 and 0 <= u, d <= 1000000. The floors are one-indexed, i.e. if there are 10 stories, s and g be in [1; 10].

Output

You must reply with the minimum numbers of pushes you must make in order to get from s to g, or output "use the stairs" if it is impossible given the conguration of the elevator.

Example

Input:
10 1 10 2 1

Output:
6
Input:
100 2 1 1 0 

Output:
use the stairs

Added by:Krzysztof Lewko
Date:2011-10-06
Time limit:1s
Source limit:50000B
Memory limit:1536MB
Cluster: Cube (Intel G860)
Languages:All except: ASM64
Resource:Nordic programming contest

hide comments
2018-12-11 21:24:04
AC in one go!!
2018-10-06 13:56:21
AC in one go!
Easy bfs :)
2018-09-04 17:28:19
A nice question for a beginner like me in bfs. It took me a lot of time to figure out the right answer and finally I did it. The problem which may occur in some of your codes can be a WA in 12th test case as mentioned by the previous comments.I will just leave a small hint to make you figure out what is wrong in your code.

HINT: All which start may not end.

Last edit: 2018-09-04 17:29:38
2018-06-13 07:11:30
Those who are getting WA in 12th testcase,note that starting floor mustn't be below the final floor.Even final floor can be below the starting floor.So when you make the comparison of cur_floor+u or cur_floor-d,use top,bottom variable to store maximum of (start,end) & minimum of (start,end) and then make comparisons.

Last edit: 2018-06-13 07:12:20
2018-05-31 09:30:36
AC in 2nd go!
nice question on bfs:)
2018-05-23 06:23:56
solved using AP ...and if ..else
2018-05-02 14:58:20
solved using if..else logic...ac in one go
2018-02-25 21:40:42
My first in BFS!!!
2018-01-14 19:20:25
ac in one go :)
2017-10-20 17:06:54
Simple BFS AC in one go -:)
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