_ButCoder Inc._ runs a programming competition site called _ButCoder_. In this site, a user is given an integer value called rating that represents his/her skill, which changes each time he/she participates in a contest. The initial value of a new user's rating is 0, and a user whose rating reaches K or higher is called _Kaiden_ ("total transmission"). Note that a user's rating may become negative.  Hikuhashi is a new user in ButCoder. It is estimated that, his rating increases by A in each of his odd-numbered contests (first, third, fifth, ...), and decreases by B in each of his even-numbered contests (second, fourth, sixth, ...).  According to this estimate, after how many contests will he become Kaiden for the first time, or will he never become Kaiden?
k,a,b=map(int,input().split())
ans=0
k-=a
if a-b<=0:
  print(-1)
elif k<=0:
  print(1)
else:
  print((k-1)//(a-b)+2)
k,a,b=map(int,input().split())
ans=0
k-=a
if k<=0:
  print(1)
elif a-b<=0:
  print(-1)
else:
  print(2*((k-1)//(a-b)+1)+1)
