#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  long long int n, x, y;
  while (cin >> x >> y >> n) {
    int flag = 0;
    long long int res = 0;
    if (x > y) swap(x, y);
    if (x >= n || y >= n) {
      cout << 0 << '\n';
      return 0;
    }
    if (x + y <= x) {
      cout << -1 << '\n';
      return 0;
    }
    if (x < 0 && y < 0 && n < 0) {
      x *= (-1);
      y *= (-1);
      n *= (-1);
    }
    if (x < 0 && y > 0 && n > y) {
      x = (-1) * x;
      res += (x / y);
      x %= y;
      if (x != 0) x = (-1) * x;
    }
    if (x < 0) {
      x += y;
      res++;
    }
    long long int temp;
    while (y < n) {
      res++;
      temp = x;
      x = y;
      y += temp;
    }
    cout << res << '\n';
  }
  return 0;
}

### Prompt

Create a solution in Cpp for the following problem:

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.

### Response

```cpp
#include <bits/stdc++.h>
using namespace std;
int main() {
  ios_base::sync_with_stdio(0);
  long long int n, x, y;
  while (cin >> x >> y >> n) {
    int flag = 0;
    long long int res = 0;
    if (x > y) swap(x, y);
    if (x >= n || y >= n) {
      cout << 0 << '\n';
      return 0;
    }
    if (x + y <= x) {
      cout << -1 << '\n';
      return 0;
    }
    if (x < 0 && y < 0 && n < 0) {
      x *= (-1);
      y *= (-1);
      n *= (-1);
    }
    if (x < 0 && y > 0 && n > y) {
      x = (-1) * x;
      res += (x / y);
      x %= y;
      if (x != 0) x = (-1) * x;
    }
    if (x < 0) {
      x += y;
      res++;
    }
    long long int temp;
    while (y < n) {
      res++;
      temp = x;
      x = y;
      y += temp;
    }
    cout << res << '\n';
  }
  return 0;
}

```