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 test{
    public static void main(String arg[]){
        Scanner sc = new Scanner(System.in);
        long x,y,m,counter = 0;
        x= sc.nextLong();
        y= sc.nextLong();
        m= sc.nextLong();
        if(x>0 || y>0){
            while(x<m && y<m){
                if(x>y){
                    if(Math.abs(y)>x){
                        long temp = Math.abs(y)/x;
                        counter+= temp;
                        y +=(x*temp);
                    }
                    y+=x;    
                }
                else{
                    if(Math.abs(x)>y){
                        long temp = Math.abs(x)/y;
                        counter+= temp;
                        x +=(y*temp);
                    }
                    x+=y;  
                } 
                counter++;
            }
            System.out.println(counter);
        } else if(x>=m || y>=m) {
            System.out.println(0);
        } else {
            System.out.println(-1);
        }
    }
}