#include <bits/stdc++.h>
int readint() {
  int t = 0;
  char c;
  c = getchar();
  while (c < '0' || c > '9') c = getchar();
  while (c >= '0' && c <= '9') {
    t = (t << 3) + (t << 1) + c - '0';
    c = getchar();
  }
  return t;
}
using namespace std;
int main() {
  int i, j, k, t;
  vector<string> vect;
  long long a, b, m;
  cin >> a >> b >> m;
  if (a >= m || b >= m) {
    puts("0");
    return 0;
  } else if (a <= 0 && b <= 0) {
    puts("-1");
    return 0;
  } else {
    long long count = 0;
    if (b > a) swap(a, b);
    if (b < 0) {
      count = (-b / a) + 1;
      b += count * a;
    }
    while (a < m && b < m) {
      count++;
      (a < b) ? (a = a + b) : (b = a + b);
    }
    cout << count << endl;
  }
  return 0;
}

### Prompt

Please provide a Cpp coded solution to the problem described below:

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>
int readint() {
  int t = 0;
  char c;
  c = getchar();
  while (c < '0' || c > '9') c = getchar();
  while (c >= '0' && c <= '9') {
    t = (t << 3) + (t << 1) + c - '0';
    c = getchar();
  }
  return t;
}
using namespace std;
int main() {
  int i, j, k, t;
  vector<string> vect;
  long long a, b, m;
  cin >> a >> b >> m;
  if (a >= m || b >= m) {
    puts("0");
    return 0;
  } else if (a <= 0 && b <= 0) {
    puts("-1");
    return 0;
  } else {
    long long count = 0;
    if (b > a) swap(a, b);
    if (b < 0) {
      count = (-b / a) + 1;
      b += count * a;
    }
    while (a < m && b < m) {
      count++;
      (a < b) ? (a = a + b) : (b = a + b);
    }
    cout << count << endl;
  }
  return 0;
}

```