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.
//package div2;

import java.io.BufferedReader;
import java.io.InputStreamReader;

public class A_PerfectPair {

    public static void main(String[] args) {
        // input reading
        BufferedReader bi = new BufferedReader(new InputStreamReader(System.in));
        String line = "";
        try {
            line = bi.readLine();
        } catch (Exception e) {
            System.out.println("Error");
        }
        String[] lineArr = line.split("\\s");

        // logic
        long x = Long.parseLong(lineArr[0]);
        long y = Long.parseLong(lineArr[1]);
        long m = Long.parseLong(lineArr[2]);

        if (x >= m || y >= m) {
            System.out.println(0);
            return;
        }
        if (x + y <= x && x + y <= y) {
            System.out.println(-1);
            return;
        }
        long count = 0;
        if (x < 0) {
            count += (-x / y);
            x += (-x / y) * y;
        } else if (y < 0) {
            count += (-y / x);
            y += (-y / x) * x;
        }
        do {    
            if (x < y) {
                x = x + y;
            } else {
                y = x + y;
            }
            count++;
        } while (x < m && y < m);

        System.out.println(count);
    }

}
