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.io.*;
import java.util.*;

public class Main {

    public Scanner sc;
    
    public void run() {
        long x = sc.nextLong();
        long y = sc.nextLong();
        long m = sc.nextLong();

        if (x <= 0 && y <= 0) {
            if (x >= m || y >= m) {
                System.out.println(0);
            }
            else {
                System.out.println(-1);
            }
            return;
        }
        
        long ans = 0;

        while (x < m && y < m) {
            long tx = Math.min(x, y);
            long ty = Math.max(x, y);

            x = tx;
            y = ty;
            
            //System.err.println(x + " " + y + " : " + ans);
            
            if (x < 0) {
                long t = (y - x) / y + 1;
                ans += t;
                x += t * y;
            }
            else {
                ans++;
                x += y;
            }
        }
        
        System.out.println(ans);
    }
    
    public static void main(String[] args) {
        Main main = new Main();
        try { main.sc = new Scanner(new FileInputStream("test.in")); }
        catch (FileNotFoundException e) { main.sc = new Scanner(System.in); }
        main.run();
    }

}