#include <bits/stdc++.h>
using namespace std;
void fastInOut() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL), cout.tie(NULL);
}
int dx[] = {0, 0, 1, -1, -1, -1, 1, 1};
int dy[] = {1, -1, 0, 0, -1, 1, -1, 1};
long long n, m, k;
long long cnt = 0;
void solve(long long x, long long y) {
  if (x >= k || y >= k) return;
  cnt++;
  if (x >= y)
    solve(x, y + x);
  else
    solve(x + y, y);
}
int main() {
  cin >> n >> m >> k;
  if (n < k && m < k && n <= 0 && m <= 0) {
    cout << -1;
    return 0;
  }
  long long a = min(n, m);
  long long b = max(n, m);
  if (b < k) {
    if (a < 0) {
      cnt += ((-a) / b);
      if ((-a) % b != 0) cnt++;
      a = b - ((-a) % b);
      if (a == b) a = 0;
    }
    n = a;
    m = b;
    solve(n, m);
  }
  cout << cnt;
}

### Prompt

Construct a CPP code solution to the problem outlined:

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;
void fastInOut() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL), cout.tie(NULL);
}
int dx[] = {0, 0, 1, -1, -1, -1, 1, 1};
int dy[] = {1, -1, 0, 0, -1, 1, -1, 1};
long long n, m, k;
long long cnt = 0;
void solve(long long x, long long y) {
  if (x >= k || y >= k) return;
  cnt++;
  if (x >= y)
    solve(x, y + x);
  else
    solve(x + y, y);
}
int main() {
  cin >> n >> m >> k;
  if (n < k && m < k && n <= 0 && m <= 0) {
    cout << -1;
    return 0;
  }
  long long a = min(n, m);
  long long b = max(n, m);
  if (b < k) {
    if (a < 0) {
      cnt += ((-a) / b);
      if ((-a) % b != 0) cnt++;
      a = b - ((-a) % b);
      if (a == b) a = 0;
    }
    n = a;
    m = b;
    solve(n, m);
  }
  cout << cnt;
}

```