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 main():
    x, y , m =map(int, input().split())
    if m<= x or m<=y:
        return "0"
    if (x <= 0 and y == 0) or (y <=0 and x==0):
        return "-1"
    lst = [x, y]
    cont = 0
    while lst[0] < m and lst[1] < m:
        # print(lst)
        if lst[0] < lst[1]:
            lst[0] += lst[1]
        else:
            lst[1] += lst[0]
        cont += 1
    return cont
print(main())
	     			  				    				  		 	 	