#include <bits/stdc++.h>
using namespace std;
const int N = 1000005;
long long n, i, j, k, q, x, y, w, a[20000000], pop, pat, h;
int main() {
  cin >> x >> y >> k;
  if (x >= k || y >= k) {
    cout << 0 << endl;
    return 0;
  }
  if (x <= 0 && y <= 0 && k > 0) {
    cout << -1 << endl;
    return 0;
  }
  if (x < k && y < k && k <= 0) {
    cout << -1 << endl;
    return 0;
  }
  if (x < y) {
    w = x;
    x = y;
    y = w;
  }
  if (y < 0) {
    pop = -y / x;
    pop++;
    pat += pop;
    y = y + pop * x;
  }
  a[1] = 1;
  a[2] = 1;
  if (x + y >= k) {
    cout << 1 + pat << endl;
    return 0;
  }
  for (i = 3;; i++) {
    a[i] = a[i - 1] + a[i - 2];
    h = a[i] * x + a[i - 1] * y;
    if (h >= k || h < 0) {
      cout << i - 1 + pat << endl;
      return 0;
    }
  }
  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;
const int N = 1000005;
long long n, i, j, k, q, x, y, w, a[20000000], pop, pat, h;
int main() {
  cin >> x >> y >> k;
  if (x >= k || y >= k) {
    cout << 0 << endl;
    return 0;
  }
  if (x <= 0 && y <= 0 && k > 0) {
    cout << -1 << endl;
    return 0;
  }
  if (x < k && y < k && k <= 0) {
    cout << -1 << endl;
    return 0;
  }
  if (x < y) {
    w = x;
    x = y;
    y = w;
  }
  if (y < 0) {
    pop = -y / x;
    pop++;
    pat += pop;
    y = y + pop * x;
  }
  a[1] = 1;
  a[2] = 1;
  if (x + y >= k) {
    cout << 1 + pat << endl;
    return 0;
  }
  for (i = 3;; i++) {
    a[i] = a[i - 1] + a[i - 2];
    h = a[i] * x + a[i - 1] * y;
    if (h >= k || h < 0) {
      cout << i - 1 + pat << endl;
      return 0;
    }
  }
  return 0;
}

```