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 C {
  public static void main(String[] args){
    FastScanner sc = new FastScanner();
    long x = sc.nextLong();
    long y = sc.nextLong();
    long m = sc.nextLong();

    long ops = 0;
    while(m > Math.max(x, y)) {
      long sum = x + y;
      if(sum <= Math.min(x, y)) {
        System.out.println(-1);
        return;
      }

      long min = Math.min(x, y);
      long max = Math.max(x, y);

      if(min < 0 && max > 0 && -min > max) {
        long mul = -min / max;
        min += mul * max;
        ops += mul;
        if(x < y) {
          x = min;
        } else {
          y = min;
        }
      } else {
        if(x < y) {
          x = sum;
        } else {
          y = sum;
        }
        ops++;
      }
    }
    System.out.println(ops);
  }

  public static class FastScanner {
    BufferedReader br;
    StringTokenizer st;

    public FastScanner(String s) {
      try {
        br = new BufferedReader(new FileReader(s));
      } catch (FileNotFoundException e) {
        e.printStackTrace();
      }
    }

    public FastScanner() {
      br = new BufferedReader(new InputStreamReader(System.in));
    }

    String nextToken() {
      while (st == null || !st.hasMoreElements()) try {
        st = new StringTokenizer(br.readLine());
      } catch (IOException e) {
        e.printStackTrace();
      }
      return st.nextToken();
    }

    int nextInt() {
      return Integer.parseInt(nextToken());
    }

    long nextLong() {
      return Long.parseLong(nextToken());
    }

    double nextDouble() {
      return Double.parseDouble(nextToken());
    }
  }
}
