# Task
John and Alice have an appointment today. 
In the morning, John starts from (`0,0`) and goes to the place (`a,b`) where he is dating. Unfortunately, John had no sense of direction at all, so he moved 1 step in a random direction(up, down, left or right) each time. For example, if John at (x,y), next step he may move to `(x+1,y), (x-1,y),(x,y+1) or (x,y-1)`. 
Obviously, when he arrived at the destination, it was already too late and Alice had already left. It's a sadly story :(
The second day, Alice asked John why he didn't go to the dating place. John said he took `s` steps to his date yesterday.
Alice wants to know whether John is lying. Please help Alice to judge.
Given two coordinates `a, b` and the step `s`, return `true` if John tells the truth, `false` otherwise.
# Input/Output
`[input]` integer `a`
The x-coordinates of the dating site.
`-10^7 <= a <= 10^7`
`[input]` integer `b`
The y-coordinates of the dating site.
`-10^7 <= b <= 10^7`
`[input]` integer `s`
A positive integer.  The steps John using.
`0 < s <= 10^9`
`[output]` a boolean value
return `true` if John tells the truth, `false` otherwise.
# Example
For `a = 3, b = 3, s = 6`, the output should be `true`.
A possible path is: 
`(0,0) -> (0,1) -> (0,2) -> (0,3) -> (1,3) -> (2,3) -> (3,3)`
For `a = 3, b = 3, s = 8`, the output should be `true`.
A possible path is: 
`(0,0) -> (0,1) -> (1,1) -> (1,2) -> (2,2) -> (2,1) -> (3,1) -> (3,2) -> (3,3)`
For `a = 4, b = 5, s = 10`, the output should be `false`.
John can't reach coordinates (a, b) using 10 steps, he's lying ;-)
def is_john_lying(a,b,s):
    delta = abs(a) + abs(b) - s
    return delta <= 0 and delta % 2 == 0
def is_john_lying(a,b,s):
    delta = abs(a) + abs(b) - s
    return delta <= 0 and delta % 2 == 0