ButCoder Inc. hosts a programming competition site called ButCoder. Users are given a skill rating that changes with each contest. A new user starts with a rating of 0 and becomes "Kaiden" when their rating reaches K or higher. Hikuhashi's rating increases by A in odd-numbered contests and decreases by B in even-numbered contests. The task is to determine after how many contests Hikuhashi becomes Kaiden for the first time, or if he never becomes Kaiden. Constraints: 1 ≤ K, A, B ≤ 10^18. Input format: K A B. Output -1 if Hikuhashi never becomes Kaiden, otherwise print the number of contests before he becomes Kaiden for the first time.

# Buggy version:
import math
K,A,B=map(int,input().split())
if A>=K:
  print(1)
elif A-B>0:
  print(1+math.ceil((K-A)/(A-B))*2)
else:
  print(-1)

# Fixed version:
from decimal import *
import math
K,A,B=map(int,input().split())
if A>=K:
  print(1)
elif A-B>0:
  print(1+math.ceil(Decimal(K-A)/Decimal(A-B))*2)
else:
  print(-1)

# Buggy version:
K,A,B = map(int,input().split())
if K<=A:
  print(1)
else:
  if A<=B:
    print(-1)
  else:
    S = (K-A)//(A-B)
    print(2*S+1)

# Fixed version:
K, A, B = map(int, input().split())

if A >= K:
  print(1)
else:
  if A-B <= 0:
    print(-1)
  else:
    S = -(-(K-A)//(A-B))
    print(S*2+1)

# Buggy version:
k, a, b = map(int, input().split())

if a <= b:
    if a < k:
        print(-1)
    else:
        print(1)
else:
    if a > k:
        print(1)
    else:
        diff = a - b
        print(2 * ((k - a) // diff) + 1)


# Fixed version:
k,a,b = map(int, input().split())
if k <= a:
  print(1)
elif b >= a:
  print(-1)
else:
  print(((k-a-1)//(a-b)+1)*2+1)

# Buggy version:
p,a,b = map(int,input().split())
if(a<=b):
  print(-1)
else:
  p-=a
  up=a-b
  if(p<=0):
    print(1)
  else
  	num=p//up+(p%up!=0)
  	print(num*2+1)


# Fixed version:
p,a,b = map(int,input().split())
if(a<=b):
  if(a>=p):
    print(1)
  else:
  	print(-1)
else:
  p-=a
  up=a-b
  if(p<=0):
    print(1)
  else:
  	num=p//up+(p%up!=0)
  	print(num*2+1)

# Buggy version:
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)

# Fixed version:
k,a,b=map(int,input().split())
if k<=a:
    print(1)
elif a-b <= 0:
    print(-1)
else:
    print(1+(k-a+(a-b)-1)//(a-b)*2)

# Buggy version:
k,a,b=map(int,input().split());print((-1 if k<a else 1)if a<=b else 2*((k-1)//(a-b))+1)

# Fixed version:
k,a,b=map(int,input().split())
print(1 if k<=a else 1+(k-b-1)//(a-b)*2 if a>b else -1)

# Buggy version:
from math import ceil
k,a,b=map(int,input().split())
k-=a
if k<=0:
  print(1)
elif a>b:
  print(1+ceil(k/(a-b))*2)
else:
  print(-1)

# Fixed version:
from math import ceil
k,a,b=map(int,input().split())
if k<=a:
  print(1)
elif a>b:
  print(1+(k-b-1)//(a-b)*2)
else:
  print(-1)

# Buggy version:
def getinputdata():

    # 配列初期化
    array_result = []
    
    data = input()

    array_result.append(data.split(" "))

    flg = 1

    try:


        while flg:

            data = input()

            array_temp = []

            if(data != ""):
                
                array_result.append(data.split(" "))

                flg = 1

            else:

                flg = 0
    finally:


        return array_result

arr_data = getinputdata()

k = int(arr_data[0][0])
a = int(arr_data[0][1])
b = int(arr_data[0][2])

cnt = (k-a) // (a-b)

#print(cnt)

if k > a:

    print(-1)

else:
    if ((k-a) % (a-b) == 0):

        print(1 + cnt * 2)

    else:

        print(1 + (cnt + 1) * 2)

    


# Fixed version:
def getinputdata():

    # 配列初期化
    array_result = []
    
    data = input()

    array_result.append(data.split(" "))

    flg = 1

    try:


        while flg:

            data = input()

            array_temp = []

            if(data != ""):
                
                array_result.append(data.split(" "))

                flg = 1

            else:

                flg = 0
    finally:


        return array_result

arr_data = getinputdata()

k = int(arr_data[0][0])
a = int(arr_data[0][1])
b = int(arr_data[0][2])

cnt = a - b

rate = a

if rate >= k:
    
    print(1)
    
elif cnt==0:

    print(-1)
else:
    
    if (k-rate) % cnt == 0:
        
        num = (k-rate) // cnt 
        
        print(1+ num*2)
    
    else:
        
        num = ((k-rate) // cnt) + 1
        
        if num>=1 :
        
            print(num*2+1)
        
        else:
            
            print(-1)

# Buggy version:
k,a,b = (int(i) for i in input().split())
num = k-a
if num<0: print(1)
elif a<b: print(-1)
else: print(((num-num%(a-b))//(a-b))*2+3)

# Fixed version:
k,a,b = (int(i) for i in input().split())
num = k-a
if num<=0: print(1)
elif a<=b: print(-1)
else: print(((num-num%(a-b))//(a-b))*2+2*(min(1,num%(a-b)))+1)

# Buggy version:
# -*- coding:utf-8 -*-
import math
k,a,b = map(int, input().split())
if a >= k:
    print(1)
else:
    if a <= b:
        print(-1)
    else:
        print((2*math.ceil((k-a)/(a-b)))+1)

# Fixed version:
# -*- coding:utf-8 -*-
from decimal import *
import math
k,a,b = map(int, input().split())
if a >= k:
    print(1)
else:
    if a <= b:
        print(-1)
    else:
        print(2*math.ceil(Decimal(k-a)/Decimal(a-b))+1)

# Buggy version:
K, A, B = map(int, input().split())
if A <= B :
   print ('-1')
elif K < B:
   print ('1')
else :
   delta = A - B
   ans = (K - A) // delta * 2 + 1
   print ('%ld' % ans)


# Fixed version:
K, A, B = map(int, input().split())
if K <= A :
   print ('1')
elif A <= B :
   print ('-1')
else :
   delta = A - B
   ans = (K - A + delta - 1) // delta * 2 + 1
   print ('%ld' % ans)

# Buggy version:
 import sys
 import math
 K, A, B = list(map(int, input().split()))

 if A >= K:
     print(1)
     sys.exit()
 elif (A - B) <= 0:
     print(-1)
     sys.exit()
 d = A - B

 p = K-A
 q = math.ceil(p/d)
 if p % d != 0:
     q += 1
 print(int(2*q + 1))

# Fixed version:
import sys
import math
K, A, B = list(map(int, input().split()))
 
if (A >= K):
    print('1')
    sys.exit()
elif (A - B) <= 0:
    print('-1')
    sys.exit()
d = A-B
p = K-A
q = int(p//d)
if ((p % d) != 0):
    q += 1
print(str(2*q + 1))