Break-Even Point

Time limit

0.35s

Memory limit

128 MB

Problem

World Electronics manufactures and sells laptops. Regardless of how many laptops it sells, it pays a fixed annual cost of A ten-thousand won. Each laptop also adds a variable production cost of B ten-thousand won.

The selling price of one laptop is C ten-thousand won. If the company sells n laptops, its total revenue is Cn and its total cost is A + Bn. In this problem, the break-even point is the smallest number of laptops for which total revenue becomes strictly greater than total cost.

Given A, B, and C, write a program that finds the break-even point.

Input

The first line contains the natural numbers A, B, and C in order, separated by spaces. Each value is at most 2,100,000,000.

Output

Print the first sales quantity that produces profit. If no break-even point exists, print -1.

Hint

The break-even point used in this problem may differ from the accounting definition.