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.
import java.util.*;

public class Main {
    static long min;
    static long max;

    static long x;
    static long y;
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);

        x = sc.nextLong();
        y = sc.nextLong();
        long m = sc.nextLong();

        min = Math.min(x, y);
        max = Math.max(x, y);

        long moves = 0;
        boolean valid = true;
        boolean zero = false;

        if (x <= 0 && y <= 0)
            valid = false;

        if (x >= m || y >= m)
            zero = true;

        if(min < 0 && max > 0) {
            moves += ((Math.abs(min) + max - 1) / max);
            min += (max * moves);
        }

        while(valid) {

            if(min >= m || max >= m)
                break;
            min += max;
            updateMinMax();
            moves++;

        }
        if(zero)
            System.out.println(0);
        else if (valid)
            System.out.println(moves);
        else
            System.out.println(-1);
    }

    private static void updateMinMax() {
        long localMin = Math.min(min, max);
        long localMax = Math.max(min, max);
        min = localMin;
        max = localMax;

    }
}