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.BufferedInputStream;

public class Solution {
  public static void main(String[] args) throws Exception {
    long x = in.nextLong(), y = in.nextLong(), n = in.nextLong();
    if (x > y) {
      long t = x;
      x = y;
      y = t;
    }

    if (y <= 0)
      System.out.println(y < n ? -1 : 0);
    else {
      long count = 0;
      if (x < 0 && y < n) {
        count += (-x / y);
        x += y * (-x / y);
      }
      while ((x < y ? y : x) < n) {
        count++;
        if (x < y)
          x += y;
        else
          y += x;
      }
      System.out.println(count);
    }
  }

  static class in {
    static BufferedInputStream in = new BufferedInputStream(System.in);

    static long nextLong() throws Exception {
      long n = 0;
      int c = in.read();
      boolean negative = false;
      while (!('0' <= c && c <= '9') && c != '-')
        c = in.read();
      if (negative = c == '-')
        c = in.read();
      while ('0' <= c && c <= '9') {
        n = (n << 1) + (n << 3) + c - '0';
        c = in.read();
      }
      return negative ? -n : n;
    }
  }
}
