#include <bits/stdc++.h>
using namespace std;
long long gCd(long long a, long long b) {
  if (b == 0) return a;
  return gCd(b, a % b);
}
long long fact(long long n) {
  long long res = 1;
  for (long long i = 2; i <= n; i++) res = (res * i) % 1000000007;
  return res;
}
long long nCr(long long n, long long r) {
  return fact(n) / (fact(r) * fact(n - r));
}
int32_t main() {
  long long x, y, m;
  cin >> x >> y >> m;
  if (x >= m | y >= m) {
    cout << 0;
  } else if (x <= 0 & y <= 0) {
    cout << -1;
  } else {
    long long result = 0;
    if (x < y) {
      long long temp = (y - x) / y;
      result += temp;
      x += temp * y;
    } else if (y < x) {
      long long temp = (x - y) / x;
      result += temp;
      y += temp * x;
    }
    while (max(x, y) < m) {
      if (x > y) {
        y += x;
        result++;
      } else {
        x += y;
        result++;
      }
    }
    cout << result;
  }
  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>
using namespace std;
long long gCd(long long a, long long b) {
  if (b == 0) return a;
  return gCd(b, a % b);
}
long long fact(long long n) {
  long long res = 1;
  for (long long i = 2; i <= n; i++) res = (res * i) % 1000000007;
  return res;
}
long long nCr(long long n, long long r) {
  return fact(n) / (fact(r) * fact(n - r));
}
int32_t main() {
  long long x, y, m;
  cin >> x >> y >> m;
  if (x >= m | y >= m) {
    cout << 0;
  } else if (x <= 0 & y <= 0) {
    cout << -1;
  } else {
    long long result = 0;
    if (x < y) {
      long long temp = (y - x) / y;
      result += temp;
      x += temp * y;
    } else if (y < x) {
      long long temp = (x - y) / x;
      result += temp;
      y += temp * x;
    }
    while (max(x, y) < m) {
      if (x > y) {
        y += x;
        result++;
      } else {
        x += y;
        result++;
      }
    }
    cout << result;
  }
  return 0;
}

```