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 JAVA):

Solution:
import java.io.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import java.util.Arrays;
import java.util.StringTokenizer;

public class Main {

    FastScanner in;
    PrintWriter out;

    Main () {
        in = new FastScanner(IO_Type.CONSOLE).getScanner();
        out = new FastWriter(IO_Type.CONSOLE).getWriter();

        //in = new FastScanner(IO_Type.TEST, "test.txt").getScanner();
        //out = new FastWriter(IO_Type.TEST, "result.txt").getWriter();

        //in = new FastScanner(IO_Type.FILE, "input.txt").getScanner();
        //out = new FastWriter(IO_Type.TEST, "output.txt").getWriter();
    }

    public static void main (String[]args) {
        Main task = new Main();
        task.solve();
        task.close();
    }

    public void close () {
        in.close();
        out.close();
    }

    public void solve () {
        int n = in.nextInt();
        int k = in.nextInt();
        int[]x = new int[n];
        int[]y = new int[n];
        for (int i = 0; i < n; i++) {
            x[i] = in.nextInt();
            y[i] = in.nextInt();
        }

        double distance = 0;
        double time = 50;

        for (int i = 1; i < n; i++) {
            distance += (Math.sqrt(Math.pow(Math.abs(x[i] - x[i - 1]), 2) + Math.pow(Math.abs(y[i] - y[i - 1]), 2))) / 0.05;
        }
        out.println(distance * k / 1000);
    }
}

class Algebra {
    /****
     *       Number of co-prime numbers on [1, n].
     *       Number a is Co-prime if gcd (a, n) == 1
     *       O (sqrt(n))
     ****/
    public static int phi(int n) {
        int result = n;
        for (int i = 2; i*i <= n; ++i) {
            if (n % i == 0) {
                while (n % i == 0) {
                    n /= i;
                }
                result -= result / i;
            }
        }
        if (n > 1) {
            result -= result / n;
        }
        return result;
    }

    /****
     *       Raise number a to power of n.
     *       O (log n)
     ****/
    public static int binpow (int a, int n) {
        int res = 1;
        while (n != 0) {
            if ((n & 1) == 1)
                res *= a;
            a *= a;
            n >>= 1;
        }
        return res;
    }

    /****
     *       Finding the greatest common divisor of two numbers.
     *       O (log min(a, b))
     ****/
    public static int gcd (int a, int b) {
        return (b != 0) ? gcd (b, a % b) : a;
    }

    /****
     *       Finding the lowest common multiple of two numbers.
     *       O (log min(a, b))
     ****/
    public static int lcm (int a, int b) {
        return a / gcd (a, b) * b;
    }

    /****
     *       Eratosthenes Sieve of numbers - [0..n]. True - simple, False - not simple.
     *       O (n log log n)
     ****/
    public static boolean[] sieveOfEratosthenes (int n) {
        boolean [] prime = new boolean[n + 1];
        Arrays.fill(prime, true);
        prime[0] = prime[1] = false;
        for (int i=2; i<=n; ++i) {
            if (prime[i]) {
                if (i * 1L * i <= n) {
                    for (int j=i*i; j<=n; j+=i) {
                        prime[j] = false;
                    }
                }
            }
        }
        return prime;
    }
}

class IO_Type {

    public static String CONSOLE = "console";
    public static String FILE = "file";
    public static String TEST = "test";

}

class FastScanner {

    BufferedReader br;
    StringTokenizer st;

    FastScanner getScanner() {
        return this;
    }

    FastScanner(String type) {
        if (type.equals("console")) {
            FastScanner(System.in);
        }
    }

    FastScanner(String type, String inFileName) {
         if (type.equals("file")) {
             File f = new File(inFileName);
             try {
                 FastScanner(new FileInputStream(f));
             } catch (FileNotFoundException e) {
                 e.printStackTrace();
             }
         }
        else if (type.equals("test")) {
             File f = new File(inFileName);
             try {
                 FastScanner(new FileInputStream(f));
             } catch (FileNotFoundException e) {
                 e.printStackTrace();
             }
         }
    }

    void FastScanner(InputStream in) {
        br = new BufferedReader(new InputStreamReader(in));
    }

    String next() {
        while (st == null || !st.hasMoreTokens()) {
            try {
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                System.err.println(e);
                return "";
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(next());
    }

    long nextLong() {
        return Long.parseLong(next());
    }

    double nextDouble() {
        return Double.parseDouble(next());
    }

    float nextFloat() {
        return Float.parseFloat(next());
    }
    BigInteger nextBigInt() {
        return new BigInteger(next());
    }

    void close() {
        try {
            br.close();
        }
        catch (IOException e) {
        }
    }
}

class FastWriter {

    PrintWriter pw;

    PrintWriter getWriter() {
        return pw;
    }

    FastWriter(String type) {
        FastWriter(type);
    }

    FastWriter (String type, String outFileName) {
        FastWriter(type, outFileName);
    }

    PrintWriter FastWriter(String type) {
        if (type.equals("console")) {
            pw = new PrintWriter(System.out);
        }
        return pw;
    }

    PrintWriter FastWriter(String type, String outFileName) {
        if (type.equals("console")) {
            pw = new PrintWriter(System.out);
        }
        else if (type.equals("test")) {
            try {
                pw = new PrintWriter(new File(outFileName));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        else if (type.equals("file")) {
            try {
                pw = new PrintWriter(new File(outFileName));
            } catch (FileNotFoundException e) {
                e.printStackTrace();
            }
        }
        return pw;
    }

}