#include <bits/stdc++.h>
using namespace std;
int main() {
  {
    long long x, y, m;
    cin >> x >> y >> m;
    if (x > y) swap(x, y);
    if (y >= m)
      cout << 0 << endl;
    else if ((x < 0 && y <= 0) || (x == 0 && y == 0)) {
      cout << -1 << endl;
    } else {
      long long k = (y - x) / y;
      if (x + k * y < y) k++;
      if (x + k * y >= m)
        cout << k << endl;
      else {
        long long f0 = 1;
        long long f1 = 1;
        long long i = 0, ans = 0;
        while (1) {
          i++;
          ans = f1 * x + (f1 * k + f0) * y;
          if (ans >= m) break;
          long long f2 = f0 + f1;
          f0 = f1;
          f1 = f2;
        }
        cout << i + k << endl;
      }
    }
  }
  return 0;
}

### Prompt

Your challenge is to write a Cpp solution to 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() {
  {
    long long x, y, m;
    cin >> x >> y >> m;
    if (x > y) swap(x, y);
    if (y >= m)
      cout << 0 << endl;
    else if ((x < 0 && y <= 0) || (x == 0 && y == 0)) {
      cout << -1 << endl;
    } else {
      long long k = (y - x) / y;
      if (x + k * y < y) k++;
      if (x + k * y >= m)
        cout << k << endl;
      else {
        long long f0 = 1;
        long long f1 = 1;
        long long i = 0, ans = 0;
        while (1) {
          i++;
          ans = f1 * x + (f1 * k + f0) * y;
          if (ans >= m) break;
          long long f2 = f0 + f1;
          f0 = f1;
          f1 = f2;
        }
        cout << i + k << endl;
      }
    }
  }
  return 0;
}

```