Today, Chef has a fencing job at hand and has to fence up a surface covering N$N$ points. 
To minimize his work, he started looking for an algorithm that had him fence the least amount of length. 
He came up with the Convex Hull algorithm, but soon realized it gave him some random shape to fence. However, Chef likes rectangles and has a favourite number M$M$. 
Help him find the minimum perimeter he has to fence if he wants to fence a rectangle, with slope of one of the sides as M$M$, to cover all the points.

-----Input:-----
- The first line contains two integers N$N$ and M$M$, the number of points and the Chef's favourite Number.
- The next n lines contain two space separated integers X$X$ and Y$Y$, the coordinates of the point.

-----Output:-----
Print a single decimal number, denoting the perimeter of the rectangle. Answer will considered correct if it has absolute error less than 10−6$10^{-6}$.

-----Constraints-----
- 2≤N≤1000000$2 \leq N \leq 1000000$
- −1000≤M≤1000$-1000 \leq M \leq 1000$
- −1000000≤X≤1000000$-1000000 \leq X \leq 1000000$
- −1000000≤Y≤1000000$-1000000 \leq Y \leq 1000000$

-----Sample Input:-----
4 1
0 1
0 -1
1 0
-1 0

-----Sample Output:-----
5.656854249492380

-----Note:-----
- As the input size is large, it is recommended to use Fast IO.

```python

USER_FILENAME = "<user_code>"
import sys, json, builtins
import math, heapq, bisect, itertools, functools, collections, statistics, fractions, decimal, operator, array, random, re, string, os, pathlib
try:
    import resource as _res
except Exception:
    _res = None
from collections import Counter, defaultdict, deque, OrderedDict
from functools import lru_cache, reduce
from itertools import accumulate, permutations, combinations, product
from math import gcd, ceil, floor, sqrt
from decimal import Decimal
try:
    from typing import *
except Exception:
    pass
try:
    sys.setrecursionlimit(1_000_000)
except Exception:
    pass
try:
    import site as _site
    try:
        _sys_sites = _site.getsitepackages() if hasattr(_site, "getsitepackages") else []
        for _p in _sys_sites:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
    try:
        _usp = _site.getusersitepackages()
        if isinstance(_usp, str):
            _usp = [_usp]
        for _p in _usp:
            if _p and _p not in sys.path:
                sys.path.append(_p)
    except Exception:
        pass
except Exception:
    pass

ns = {"__name__": "__main__"}
for _k, _v in list(globals().items()):
    if not _k.startswith("_"):
        ns[_k] = _v
_CODE = 'from math import sqrt\r\nN,M  = input().split()\r\nN,M = int(N),float(M)\r\nif(M==0):\r\n    n = 0\r\n    while(n<N):\r\n        \r\n        xi,yi = input().split()\r\n        xi,yi = float(xi),float(yi)\r\n        if n==0:\r\n            c1_min = c1_max = xi\r\n            c2_min = c2_max = yi\r\n        else:\r\n            if c1_min>xi:\r\n                c1_min  = xi\r\n            elif c1_max<xi:\r\n                c1_max = xi\r\n            \r\n            if c2_min>yi:\r\n                c2_min  = yi\r\n            elif c2_max<yi:\r\n                c2_max = yi\r\n        \r\n        n+=1\r\n    perimeter = 2*(c2_max-c2_min+c1_max-c1_min)\r\nelse:\r\n    n = 0\r\n    while(n<N):\r\n        xi,yi = input().split()\r\n        xi,yi = float(xi),float(yi)\r\n        temp1 = yi-M*xi\r\n        temp2 = yi+xi/M\r\n        if n==0:\r\n            c1_min = c1_max = temp1\r\n            c2_min = c2_max = temp2\r\n        else:\r\n            if c1_min>temp1:\r\n                c1_min  = temp1\r\n            elif c1_max<temp1:\r\n                c1_max = temp1\r\n            \r\n            if c2_min>temp2:\r\n                c2_min  = temp2\r\n            elif c2_max<temp2:\r\n                c2_max = temp2\r\n        n+=1\r\n    perimeter = 2*(((c1_max-c1_min)/sqrt(1.0+M*M))+\r\n    ((c2_max-c2_min)/sqrt(1.0+1.0/(M*M))));\r\nprint(perimeter)'
_co = compile(_CODE, USER_FILENAME, "exec")
exec(_co, ns, ns)

```

Measured memory_bytes: 13557