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.
fibs = {}



if __name__=='__main__':
    inp = raw_input()
    arr=inp.split(" ")
    x=int(arr[0])
    y=int(arr[1])
    m=int(arr[2])
    ans = 0
    if max(x,y)>=m:
        print "0"
    elif x<1 and y<1:
        print "-1"
    else:
        if min(x,y)<1:
            ans+=(1-min(x,y))/max(x,y)
            a=max(x,y)
            b=min(x,y)
            y=b+a*ans
            x=a
        while True:
            ans+=1
            a = max(x,y)
            b = min(x,y)
            x=a+b
            y=a
            if max(x,y)>=m:
                print ans
                break
        
