#include <bits/stdc++.h>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
long long n, x, y, m, ans = 0;
int32_t main() {
  cin >> x;
  cin >> y;
  cin >> m;
  if (x >= m || y >= m) {
    cout << "0";
    return 0;
  }
  if (x <= 0 && y <= 0) {
    cout << "-1";
    return 0;
  }
  if (min(x, y) <= 0 && max(x, y) > 0) {
    if (x < y) {
      ans = -x / y;
      x = x % y;
    } else {
      ans = -y / x;
      y = y % x;
    }
  }
  while (x < m && y < m) {
    if (x < y) {
      x = x + y;
    } else {
      y = y + x;
    }
    ans++;
  }
  cout << ans;
  return 0;
}

### Prompt

Your task is to create 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>
#pragma GCC optimize("O3")
#pragma GCC optimize("Ofast")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
using namespace std;
long long n, x, y, m, ans = 0;
int32_t main() {
  cin >> x;
  cin >> y;
  cin >> m;
  if (x >= m || y >= m) {
    cout << "0";
    return 0;
  }
  if (x <= 0 && y <= 0) {
    cout << "-1";
    return 0;
  }
  if (min(x, y) <= 0 && max(x, y) > 0) {
    if (x < y) {
      ans = -x / y;
      x = x % y;
    } else {
      ans = -y / x;
      y = y % x;
    }
  }
  while (x < m && y < m) {
    if (x < y) {
      x = x + y;
    } else {
      y = y + x;
    }
    ans++;
  }
  cout << ans;
  return 0;
}

```