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.*;
import java.math.BigInteger;
public class PerfectPair{
    public static void main(String args[]){
        Scanner ob=new Scanner(System.in);
        //System.out.println("enter n");
        BigInteger a,b,c;
        a=ob.nextBigInteger();
        b=ob.nextBigInteger();
        c=ob.nextBigInteger();
        if(a.compareTo(c)>=0||b.compareTo(c)>=0){
            System.out.println("0");
            System.exit(0);
        }
        BigInteger zero=new BigInteger("0");
        if(a.compareTo(zero)<=0&&b.compareTo(zero)<=0){
            System.out.println("-1");
            System.exit(0);
        }
        BigInteger count=new BigInteger("0");
        if(a.compareTo(zero)<0){
            count=a.divide(b);
            count=count.multiply(new BigInteger("-1"));
            a=a.add(count.multiply(b));
        }
        else if(b.compareTo(zero)<0){
            count=b.divide(a);
            count=count.multiply(new BigInteger("-1"));
            b=b.add(count.multiply(a));
        }
        BigInteger one=new BigInteger("1");
        while(a.compareTo(c)<0&&b.compareTo(c)<0){
            BigInteger sum=a.add(b);
            if(a.compareTo(b)>0)
                b=sum;
            else
                a=sum;
            count=count.add(one);
        }
        System.out.println(count);
    }
}