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.
def swap(x, y):
    return y, x

def run(line):
    #print line
    x, y, m = [int(i) for i in line.split()]

    if x <= 0 and y <= 0 and max(x, y, x+y) < m:
        return -1

    if x >= m or y >= m:
        return 0

    if y > x:
        x, y = swap(x, y)

    ops = 1
    if y <= 0:
        addOps = (-y / x) + 1
        ops = addOps
        y += x * addOps
        if y == 0:
            y += x
            ops += 1
        ops += 1

    if y > x:
        x, y = swap(x, y)

    #print x, y, ops
    
    f1 = 1
    f2 = 1
    #print f1, f2, ops, max(f1, f2) * x + min(f1, f2) * y, m
    while max(f1, f2) * x + min(f1, f2) * y < m:
        f2 = f1 + f2
        f1, f2 = swap(f1, f2)
        ops += 1
        #print f1, f2, ops, max(f1, f2) * x + min(f1, f2) * y, m
    return ops

while 1:
    try:
        line = raw_input()
        print run(line)
    except EOFError:
        break
