Problem: Mr. Scrooge, a very busy man, decided to count the time he wastes on all sorts of useless stuff to evaluate the lost profit. He has already counted the time he wastes sleeping and eating. And now Mr. Scrooge wants to count the time he has wasted signing papers.

Mr. Scrooge's signature can be represented as a polyline A1A2... An. Scrooge signs like that: first it places a pen at the point A1, then draws a segment from point A1 to point A2, then he draws a segment from point A2 to point A3 and so on to point An, where he stops signing and takes the pen off the paper. At that the resulting line can intersect with itself and partially repeat itself but Scrooge pays no attention to it and never changes his signing style. As Scrooge makes the signature, he never takes the pen off the paper and his writing speed is constant — 50 millimeters per second.

Scrooge signed exactly k papers throughout his life and all those signatures look the same.

Find the total time Scrooge wasted signing the papers.

Input

The first line contains two integers n and k (2 ≤ n ≤ 100, 1 ≤ k ≤ 1000). Each of the following n lines contains the coordinates of the polyline's endpoints. The i-th one contains coordinates of the point Ai — integers xi and yi, separated by a space.

All points Ai are different. The absolute value of all coordinates does not exceed 20. The coordinates are measured in millimeters.

Output

Print one real number — the total time Scrooges wastes on signing the papers in seconds. The absolute or relative error should not exceed 10 - 6.

Examples

Input

2 1
0 0
10 0


Output

0.200000000

Input

5 10
3 1
-5 6
-2 -1
3 2
10 0


Output

6.032163204

Input

6 10
5 0
4 0
6 0
3 0
7 0
2 0


Output

3.000000000

Solution (in PYTHON3):

Solution:
#pyrival orz
import os
import sys
import math
from io import BytesIO, IOBase


input = sys.stdin.readline
############ ---- Input Functions ---- ############
def inp():
    return(int(input()))
def inlt():
    return(list(map(int,input().split())))
def insr():
    s = input()
    return(list(s[:len(s) - 1]))
def invr():
    return(map(int,input().split()))

############ ---- Dijkstra with path ---- ############
def dijkstra(start, distance, path, n):
    # requires n == number of vertices in graph,
    # adj == adjacency list with weight of graph

    visited = [False for _ in range(n)]  # To keep track of vertices that are visited
    distance[start] = 0  # distance of start node from itself is 0

    for i in range(n):
        v = -1  # Initialize v == vertex from which its neighboring vertices' distance will be calculated
        for j in range(n):
            # If it has not been visited and has the lowest distance from start
            if not visited[v] and (v == -1 or distance[j] < distance[v]):
                v = j

        if distance[v] == math.inf:
            break

        visited[v] = True  # Mark as visited

        for edge in adj[v]:
            destination = edge[0]  # Neighbor of the vertex
            weight = edge[1]  # Its corresponding weight

            if distance[v] + weight < distance[destination]:  # If its distance is less than the stored distance
                distance[destination] = distance[v] + weight  # Update the distance
                path[destination] = v  # Update the path
        

def gcd(a, b):
    if b == 0:
        return a
    else:
        return gcd(b, a%b)

def lcm(a, b):
    return (a*b)//gcd(a, b)

def ncr(n, r):
    return math.factorial(n)//(math.factorial(n-r)*math.factorial(r))

def npr(n, r):
    return math.factorial(n)//math.factorial(n-r)

def seive(n):
    primes = [True]*(n+1)
    ans = []

    for i in range(2, n):
        if not primes[i]:
            continue

        j = 2*i
        while j <= n:
            primes[j] = False
            j += i

    for p in range(2, n+1):
        if primes[p]:
            ans += [p]

    return ans

def factors(n):
    factors = []

    x = 1
    while x*x <= n:

        if n % x == 0:
            if n // x == x:
                factors.append(x)
            else:
                factors.append(x)
                factors.append(n//x)

        x += 1

    return factors

# Functions: list of factors, seive of primes, gcd of two numbers,
# lcm of two numbers, npr, ncr

def main():
    try:
        n, k = invr()
        calc = 0
        prev = []
        for i in range(n):
            x, y = invr()
            if prev:
                calc += math.sqrt((x - prev[0])**2 + (y - prev[1])**2)

            prev = [x, y]

        print(calc*k/50)

    except Exception as e:
        print(e)

        

# region fastio

BUFSIZE = 8192


class FastIO(IOBase):
    newlines = 0

    def __init__(self, file):
        self._fd = file.fileno()
        self.buffer = BytesIO()
        self.writable = "x" in file.mode or "r" not in file.mode
        self.write = self.buffer.write if self.writable else None

    def read(self):
        while True:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            if not b:
                break
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines = 0
        return self.buffer.read()

    def readline(self):
        while self.newlines == 0:
            b = os.read(self._fd, max(os.fstat(self._fd).st_size, BUFSIZE))
            self.newlines = b.count(b"\n") + (not b)
            ptr = self.buffer.tell()
            self.buffer.seek(0, 2), self.buffer.write(b), self.buffer.seek(ptr)
        self.newlines -= 1
        return self.buffer.readline()

    def flush(self):
        if self.writable:
            os.write(self._fd, self.buffer.getvalue())
            self.buffer.truncate(0), self.buffer.seek(0)


class IOWrapper(IOBase):
    def __init__(self, file):
        self.buffer = FastIO(file)
        self.flush = self.buffer.flush
        self.writable = self.buffer.writable
        self.write = lambda s: self.buffer.write(s.encode("ascii"))
        self.read = lambda: self.buffer.read().decode("ascii")
        self.readline = lambda: self.buffer.readline().decode("ascii")


sys.stdin, sys.stdout = IOWrapper(sys.stdin), IOWrapper(sys.stdout)
input = lambda: sys.stdin.readline().rstrip("\r\n")

# endregion

if __name__ == "__main__":
    main()