Frog Rendezvous

Given a pond of length $L$, two frogs start swimming simultaneously from opposite banks. The first frog starts at the left bank and swims to the right with constant speed $V_1$, while the second frog starts at the right bank and swims to the left with constant speed $V_2$. Whenever a frog reaches a bank, it instantly reverses direction and continues swimming at the same speed. In a total time of $T$ time units, determine the number of times the two frogs meet.

Note: Let $X = \frac{(V_1+V_2)T}{L}$. If $X$ is an integer and positive, then the answer is $X-1$, otherwise it is $\lfloor X \rfloor$. (Meetings exactly at time $T$ when both frogs reach the bank are not counted as a meeting.)

inputFormat

Input consists of a single line containing four space-separated positive numbers: $L$, $V_1$, $V_2$, and $T$.

outputFormat

Output a single integer representing the number of times the two frogs meet within $T$ time units.

sample

10 1 1 10

1