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

public class PerfectPair {
	public static void main(String[] args) throws Exception {
		BufferedReader k = new BufferedReader(new InputStreamReader(System.in));
		String[] s = k.readLine().split(" ");
		long a = Long.parseLong(s[0]);
		long b = Long.parseLong(s[1]);
		long m = Long.parseLong(s[2]);
		if (b > a) {
			long t = b;
			b = a;
			a = t;
		}
		if(m<=a||m<=b){
			System.out.println(0);
			return;
		}
		if(a==0&&b==0){
			System.out.println(-1);
			return;
		}
		long counter = 0;
		long x=10000000;
		
		if(-b>x&&a<1000){
			counter=(-b/a);
			b=(-b%a);
		}
		
		
		if ((a > 0)  ) {
			
			while (a < m && b < m) {
				if (b > a) {
					long t = b;
					b = a;
					a = t;
				}
				b += a;
				counter++;

			}
		} else
			counter = -1;
		System.out.println(counter);
	}
}
