Let us call a pair of integer numbers m-perfect, if at least one number in the pair is greater than or equal to m. Thus, the pairs (3, 3) and (0, 2) are 2-perfect while the pair (-1, 1) is not.

Two integers x, y are written on the blackboard. It is allowed to erase one of them and replace it with the sum of the numbers, (x + y).

What is the minimum number of such operations one has to perform in order to make the given pair of integers m-perfect?

Input

Single line of the input contains three integers x, y and m ( - 1018 ≤ x, y, m ≤ 1018).

Please, do not use the %lld specifier to read or write 64-bit integers in C++. It is preffered to use the cin, cout streams or the %I64d specifier.

Output

Print the minimum number of operations or "-1" (without quotes), if it is impossible to transform the given pair to the m-perfect one.

Examples

Input

1 2 5


Output

2


Input

-1 4 15


Output

4


Input

0 -1 5


Output

-1

Note

In the first sample the following sequence of operations is suitable: (1, 2) <image> (3, 2) <image> (5, 2).

In the second sample: (-1, 4) <image> (3, 4) <image> (7, 4) <image> (11, 4) <image> (15, 4).

Finally, in the third sample x, y cannot be made positive, hence there is no proper sequence of operations.
s = raw_input().split()
(x, y, z) = (int(s[0]), int(s[1]), int(s[2]))

if x > y:
    tmp = x
    x = y
    y = tmp

if y >= z:
    print 0
elif y <= 0:
    print -1
else:
    r = 0
    a = 0
    b = 1
    if x < 0:
        if x % y:
            r = (-x/y)+1
            x = r*y + x
        else:
            r = -x/y
            x = 0
    while (a*x + b*y) < z:
        c = b
        b = a+b
        a = c
        r += 1
    print r

#s = raw_input()

#i = 0
#h = 0
#r = 0
#while i < (len(s)-4):
#    if (s[i:i+5] == 'heavy'):
#        h += 1
#        i += 4
#    elif (s[i:i+5] == 'metal'):
#        r += h
#        i += 4
#    i += 1

#print r

#s = raw_input()
#s1 = s.split()
#n = int(s1[0])
#k = int(s1[1])

#b = n/2 + (n%2)

#if k <= b:
#    print k*2-1
#else:
#    print (k-b)*2

