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?
Single line of the input contains three integers *x*, *y* and *m* ( - 10<sup class="upper-index">18</sup> ≤ *x*, *y*, *m* ≤ 10<sup class="upper-index">18</sup>).

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.
def ppair(x, y, m):
    if x >= y:
        x, y = y, x
    n = 0
    while x < m and y < m:
        if n > 10: break
        sum = x + y
        if sum < x:
            n = -1
            break
        elif sum >= m:
            x, y = x, sum
        else:
            x, y = y, sum
        n = n + 1
    return n

if __name__ == '__main__':
    x, y, m = input().split()
    n = ppair(int(x), int(y), int(m))
    print(n)
