#include <bits/stdc++.h>
using namespace std;
long n, v, d = 0, c, m1;
struct o {
  long x;
  long y;
};
int b[1000005], inf = 100000000;
vector<int> a[100001];
long l[105][105] = {0}, s = 0;
bool used[100001];
bool func(o a, o b) { return a.x < b.x; }
int m, mine[100001], ind[105], raod = 0;
void dfs(int v) {
  used[v] = 1;
  mine[v] = raod;
  for (int k = 0; k < a[v].size(); ++k)
    if (!used[a[v][k]]) dfs(a[v][k]);
}
long long x, y, z;
int main() {
  cin >> x >> y >> z;
  if (x >= z || y >= z) {
    cout << 0;
    return 0;
  }
  if (x <= 0 && y <= 0) {
    cout << -1;
    return 0;
  }
  long long t = max(x, y);
  long long u = min(x, y);
  long long raod = 0;
  if (u < 0) {
    raod += abs(u / t);
    if (u % t != 0) ++raod;
    u = u + raod * t;
  }
  t = max(t, u);
  u = min(t, u);
  while (t < z) {
    u = t + u;
    ++raod;
    if (u > t) swap(u, t);
  }
  cout << raod;
  return 0;
}

### Prompt

Create a solution in cpp for 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 n, v, d = 0, c, m1;
struct o {
  long x;
  long y;
};
int b[1000005], inf = 100000000;
vector<int> a[100001];
long l[105][105] = {0}, s = 0;
bool used[100001];
bool func(o a, o b) { return a.x < b.x; }
int m, mine[100001], ind[105], raod = 0;
void dfs(int v) {
  used[v] = 1;
  mine[v] = raod;
  for (int k = 0; k < a[v].size(); ++k)
    if (!used[a[v][k]]) dfs(a[v][k]);
}
long long x, y, z;
int main() {
  cin >> x >> y >> z;
  if (x >= z || y >= z) {
    cout << 0;
    return 0;
  }
  if (x <= 0 && y <= 0) {
    cout << -1;
    return 0;
  }
  long long t = max(x, y);
  long long u = min(x, y);
  long long raod = 0;
  if (u < 0) {
    raod += abs(u / t);
    if (u % t != 0) ++raod;
    u = u + raod * t;
  }
  t = max(t, u);
  u = min(t, u);
  while (t < z) {
    u = t + u;
    ++raod;
    if (u > t) swap(u, t);
  }
  cout << raod;
  return 0;
}

```