#include <bits/stdc++.h>
using namespace std;
long long con, a, b, m;
int main() {
  con = 0;
  cin >> a >> b >> m;
  if (m == 0) {
    if (a * b > 0) {
      cout << -1 << endl;
      return 0;
    } else {
      cout << 0 << endl;
      return 0;
    };
  } else if (m > 0) {
    if (a > b) swap(a, b);
    if (a <= 0 && b <= 0) {
      cout << -1 << endl;
      return 0;
    };
    if (b >= m) {
      cout << 0 << endl;
      return 0;
    };
    if (a < 0) con = ceil(a * -1.0 / b), a += b * con;
    if (a > b) swap(a, b);
    while (b < m) {
      long long tmp = a + b;
      a = b;
      b = tmp;
      con++;
    }
    cout << con << endl;
  } else if (m < 0) {
    if (a < m && b < m) {
      cout << -1 << endl;
      return 0;
    } else {
      cout << 0 << endl;
      return 0;
    };
  }
}

### Prompt

Generate 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;
long long con, a, b, m;
int main() {
  con = 0;
  cin >> a >> b >> m;
  if (m == 0) {
    if (a * b > 0) {
      cout << -1 << endl;
      return 0;
    } else {
      cout << 0 << endl;
      return 0;
    };
  } else if (m > 0) {
    if (a > b) swap(a, b);
    if (a <= 0 && b <= 0) {
      cout << -1 << endl;
      return 0;
    };
    if (b >= m) {
      cout << 0 << endl;
      return 0;
    };
    if (a < 0) con = ceil(a * -1.0 / b), a += b * con;
    if (a > b) swap(a, b);
    while (b < m) {
      long long tmp = a + b;
      a = b;
      b = tmp;
      con++;
    }
    cout << con << endl;
  } else if (m < 0) {
    if (a < m && b < m) {
      cout << -1 << endl;
      return 0;
    } else {
      cout << 0 << endl;
      return 0;
    };
  }
}

```