Problem: There are n sharks who grow flowers for Wet Shark. They are all sitting around the table, such that sharks i and i + 1 are neighbours for all i from 1 to n - 1. Sharks n and 1 are neighbours too.

Each shark will grow some number of flowers si. For i-th shark value si is random integer equiprobably chosen in range from li to ri. Wet Shark has it's favourite prime number p, and he really likes it! If for any pair of neighbouring sharks i and j the product si·sj is divisible by p, then Wet Shark becomes happy and gives 1000 dollars to each of these sharks.

At the end of the day sharks sum all the money Wet Shark granted to them. Find the expectation of this value.

Input

The first line of the input contains two space-separated integers n and p (3 ≤ n ≤ 100 000, 2 ≤ p ≤ 109) — the number of sharks and Wet Shark's favourite prime number. It is guaranteed that p is prime.

The i-th of the following n lines contains information about i-th shark — two space-separated integers li and ri (1 ≤ li ≤ ri ≤ 109), the range of flowers shark i can produce. Remember that si is chosen equiprobably among all integers from li to ri, inclusive.

Output

Print a single real number — the expected number of dollars that the sharks receive in total. You answer will be considered correct if its absolute or relative error does not exceed 10 - 6. 

Namely: let's assume that your answer is a, and the answer of the jury is b. The checker program will consider your answer correct, if <image>.

Examples

Input

3 2
1 2
420 421
420420 420421


Output

4500.0


Input

3 5
1 4
2 3
11 14


Output

0.0

Note

A prime number is a positive integer number that is divisible only by 1 and itself. 1 is not considered to be prime.

Consider the first sample. First shark grows some number of flowers from 1 to 2, second sharks grows from 420 to 421 flowers and third from 420420 to 420421. There are eight cases for the quantities of flowers (s0, s1, s2) each shark grows:

  1. (1, 420, 420420): note that s0·s1 = 420, s1·s2 = 176576400, and s2·s0 = 420420. For each pair, 1000 dollars will be awarded to each shark. Therefore, each shark will be awarded 2000 dollars, for a total of 6000 dollars.
  2. (1, 420, 420421): now, the product s2·s0 is not divisible by 2. Therefore, sharks s0 and s2 will receive 1000 dollars, while shark s1 will receive 2000. The total is 4000.
  3. (1, 421, 420420): total is 4000
  4. (1, 421, 420421): total is 0. 
  5. (2, 420, 420420): total is 6000. 
  6. (2, 420, 420421): total is 6000. 
  7. (2, 421, 420420): total is 6000. 
  8. (2, 421, 420421): total is 4000.



The expected value is <image>.

In the second sample, no combination of quantities will garner the sharks any money.

Solution (in JAVA):

Solution:
//import com.sun.org.apache.xpath.internal.operations.String;

import java.io.*;
import java.util.*;


public class scratch_25 {
   // int count=0;
    //static long count=0;
    static class Reader {
        static BufferedReader reader;
        static StringTokenizer tokenizer;

        /**
         * call this method to initialize reader for InputStream
         */
        static void init(InputStream input) {
            reader = new BufferedReader(
                    new InputStreamReader(input));
            tokenizer = new StringTokenizer("");
        }

        /**
         * get next word
         */
        static String next() throws IOException {
            while (!tokenizer.hasMoreTokens()) {
                //TODO add check for eof if necessary
                tokenizer = new StringTokenizer(
                        reader.readLine());
            }
            return tokenizer.nextToken();
        }

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

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

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

    public static class Graph{
        public static class Vertex{
            HashMap<Integer,Integer> nb= new HashMap<>();     // for neighbours of each vertex
        }

        public static HashMap<Integer,Vertex> vt;   // for vertices(all)

        public Graph(){
            vt= new HashMap<>();
        }

        public static int numVer(){
            return vt.size();
        }

        public static boolean contVer(int ver){
            return vt.containsKey(ver);
        }

        public static void addVer(int ver){
            Vertex v= new Vertex();
            vt.put(ver,v);
        }

        public static int numEdg(){
            int count=0;
            ArrayList<Integer> vrtc= new ArrayList<>(vt.keySet());
            for (int i = 0; i <vrtc.size() ; i++) {
                count+=(vt.get(vrtc.get(i))).nb.size();
            }
            return count/2;
        }

        public static boolean contEdg(int ver1, int ver2){
            if(vt.get(ver1)==null || vt.get(ver2)==null){
                return false;
            }

            Vertex v= vt.get(ver1);
            if(v.nb.containsKey(ver2)){
                return true;
            }
            return false;
        }

        public static void addEdge(int ver1, int ver2, int weight){
            if(!vt.containsKey(ver1) || !vt.containsKey(ver2)){
                return;
            }
            Vertex v1= vt.get(ver1);
            Vertex v2= vt.get(ver2);
            v1.nb.put(ver2,weight);                                 // if previously there is an edge, then this replaces that edge
            v2.nb.put(ver1,weight);
        }

        public static void delEdge(int ver1, int ver2){

            if(!vt.containsKey(ver1) || !vt.containsKey(ver2)){
                return;
            }

            vt.get(ver1).nb.remove(ver2);
            vt.get(ver2).nb.remove(ver1);

        }

        public static void delVer(int ver){
            if(!vt.containsKey(ver)){
                return;
            }
            Vertex v1= vt.get(ver);
            ArrayList<Integer> arr= new ArrayList<>(v1.nb.keySet());
            for (int i = 0; i <arr.size() ; i++) {
                int s= arr.get(i);
                vt.get(s).nb.remove(ver);
            }
            vt.remove(ver);
        }

        public class Pair{
            int vname;
            ArrayList<Integer> psf= new ArrayList<>();       // path so far
            int dis;
            int col;
        }









        public HashMap<Integer,Integer> bfs(int src){
            HashMap<Integer, Boolean> prcd= new HashMap<>();    // jo jo ho chuke hain unke liye

            HashMap<Integer, Integer> ans= new HashMap<>();

            LinkedList<Pair> queue= new LinkedList<>();      // for bfs queue

            Pair strtp= new Pair();

            strtp.vname= src;

            ArrayList<Integer> ar= new ArrayList<>();
            ar.add(src);

            strtp.psf= ar;
            strtp.dis=0;

            queue.addLast(strtp);

            while(!queue.isEmpty()){

                Pair rp =  queue.removeFirst();

                if(prcd.containsKey(rp.vname)){
                    continue;
                }
                prcd.put(rp.vname,true);
                ans.put(rp.vname,rp.dis);

//                if(contEdg(rp.vname,dst)){
//                    return true;
//                }

                Vertex a= vt.get(rp.vname);
                ArrayList<Integer> arr= new ArrayList<>(a.nb.keySet());
                for (int i = 0; i <arr.size() ; i++) {
                    int s= arr.get(i);
                    if(!prcd.containsKey(s)){
                        Pair np = new Pair();
                        np.vname= s;
                        np.dis+=rp.dis+a.nb.get(s);
                        np.psf.addAll(rp.psf);
                        np.psf.add(s);
//                        np.psf.add(s);
//                         np.psf= rp.psf+" "+s;
                        queue.addLast(np);
                    }

                }
            }
            return ans;

            //   return false;
        }








        public HashMap<Integer,Integer> dfs(int src){
            HashMap<Integer, Boolean> prcd= new HashMap<>();    // jo jo ho chuke hain unke liye

            HashMap<Integer, Integer> ans= new HashMap<>();

            LinkedList<Pair> stack= new LinkedList<>();      // for bfs queue

            Pair strtp= new Pair();

            strtp.vname= src;

            ArrayList<Integer> ar= new ArrayList<>();
            ar.add(src);

            strtp.psf= ar;
            strtp.dis=0;

            stack.addFirst(strtp);

            while(!stack.isEmpty()){

                Pair rp =  stack.removeFirst();

                if(prcd.containsKey(rp.vname)){
                    continue;
                }
                prcd.put(rp.vname,true);
                ans.put(rp.vname,rp.dis);

//                if(contEdg(rp.vname,dst)){
//                    return true;
//                }

                Vertex a= vt.get(rp.vname);
                ArrayList<Integer> arr= new ArrayList<>(a.nb.keySet());
                for (int i = 0; i <arr.size() ; i++) {
                    int s= arr.get(i);
                    if(!prcd.containsKey(s)){
                        Pair np = new Pair();
                        np.vname= s;
                        np.dis+=rp.dis+a.nb.get(s);
                        np.psf.addAll(rp.psf);
                        np.psf.add(s);
//                        np.psf.add(s);
//                         np.psf= rp.psf+" "+s;
                        stack.addFirst(np);
                    }

                }
            }
            return ans;

            //   return false;
        }






        public boolean isCycle(){
            HashMap<Integer, Boolean> prcd= new HashMap<>();    // jo jo ho chuke hain unke liye

            //   HashMap<Integer, Integer> ans= new HashMap<>();

            LinkedList<Pair> queue= new LinkedList<>();      // for bfs queue



            ArrayList<Integer> keys = new ArrayList<>(vt.keySet());
            for (int i = 0; i <keys.size(); i++) {
                int cur= keys.get(i);
                if(prcd.containsKey(cur)){
                    continue;
                }

                Pair sp = new Pair();
                sp.vname= cur;
                ArrayList<Integer> as= new ArrayList<>();
                as.add(cur);
                sp.psf= as;

                queue.addLast(sp);

                while(!queue.isEmpty()){




                    Pair rp= queue.removeFirst();
                    if(prcd.containsKey(rp.vname)){
                        return true;
                    }

                    prcd.put(rp.vname,true);




                    Vertex v1= vt.get(rp.vname);
                    ArrayList<Integer> nbrs= new ArrayList<>(v1.nb.keySet());
                    for (int j = 0; j <nbrs.size() ; j++) {
                        int u= nbrs.get(j);
                        Pair np= new Pair();
                        np.vname= u;
                        queue.addLast(np);
                    }
                }

            }
            return false;
        }






        public  ArrayList<ArrayList<Integer>> genConnctdComp(){
            HashMap<Integer, Boolean> prcd= new HashMap<>();    // jo jo ho chuke hain unke liye

            ArrayList<ArrayList<Integer>> ans= new ArrayList<>();

            //   HashMap<Integer, Integer> ans= new HashMap<>();

            LinkedList<Pair> queue= new LinkedList<>();      // for bfs queue

            //  int con=-1;

            ArrayList<Integer> keys = new ArrayList<>(vt.keySet());
            for (int i = 0; i <keys.size(); i++) {
                int cur= keys.get(i);
                if(prcd.containsKey(cur)){
                    //return true;
                    continue;
                }
                int count=0;
                ArrayList<Integer> fu= new ArrayList<>();
                fu.add(cur);


                Pair sp = new Pair();
                sp.vname= cur;
                ArrayList<Integer> as= new ArrayList<>();
                as.add(cur);
                sp.psf= as;

                queue.addLast(sp);

                while(!queue.isEmpty()){




                    Pair rp= queue.removeFirst();
                    if(prcd.containsKey(rp.vname)){
                        //return true;
                        continue;
                    }

                    prcd.put(rp.vname,true);
                    fu.add(rp.vname);



                    Vertex v1= vt.get(rp.vname);
                    ArrayList<Integer> nbrs= new ArrayList<>(v1.nb.keySet());
                    for (int j = 0; j <nbrs.size() ; j++) {
                        int u= nbrs.get(j);
                        if(!prcd.containsKey(u)){
                            count++;
                        Pair np= new Pair();
                        np.vname= u;
                        queue.addLast(np);
                    }
                }}
                fu.add(count);
                ans.add(fu);

            }
            //return false;
            return ans;

        }

        public boolean isBip(int src){                       // only for connected graph

            HashMap<Integer,Integer> clr= new HashMap<>();
            // colors are 1 and -1


            LinkedList<Integer>q = new LinkedList<Integer>();
            clr.put(src,1);
            q.add(src);


            while(!q.isEmpty()){

                int u = q.getFirst();
                q.pop();

                ArrayList<Integer> arr= new ArrayList<>(vt.keySet());

                for (int i = 0; i <arr.size() ; ++i) {

                    int x= arr.get(i);

                    if(vt.get(u).nb.containsKey(x) && !clr.containsKey(x)){

                        if(clr.get(u)==1){
                            clr.put(x,-1);
                        }
                        else{
                            clr.put(x,1);
                        }
                        q.push(x);
                    }

                    else if(vt.get(u).nb.containsKey(x) && (clr.get(x)==clr.get(u))){
                        return false;
                    }

                }
            }
            return true;
        }

















        public static void printGr() {
            ArrayList<Integer> arr= new ArrayList<>(vt.keySet());
            for (int i = 0; i <arr.size() ; i++) {
                int ver= arr.get(i);
                Vertex v1= vt.get(ver);
                ArrayList<Integer> arr1= new ArrayList<>(v1.nb.keySet());
                for (int j = 0; j <arr1.size() ; j++) {
                    System.out.println(ver+"-"+arr1.get(j)+":"+v1.nb.get(arr1.get(j)));
                }

            }
        }
    }

    static class Cus implements Comparable<Cus>{
        int size;
        int mon;
        int num;
        public Cus(int size,int mon,int num){
            this.size=size;
            this.mon=mon;
            this.num=num;
        }
        @Override
        public int compareTo(Cus o){
            if(this.mon!=o.mon){
                return this.mon-o.mon;}

            else{
                return o.size-this.size;
            }

        }



    }

    static class Table implements Comparable<Table>{
        int go;
        int cum;
        int cost;
        public Table(int go,int cum,int cost){
            this.go=go;
            this.cum=cum;
            this.cost=cost;
        }
        @Override
        public int compareTo(Table o){
            if(this.go==o.go){
                return this.cum-o.cum;
            }
            return this.go-o.go;

        }


    }
    static class Table1 implements Comparable<Table1>{
        int go;
        int cum;
        int cost;
        public Table1(int go,int cum,int cost){
            this.go=go;
            this.cum=cum;
            this.cost=cost;
        }
        @Override
        public int compareTo(Table1 o){
            return this.cost-o.cost;


        }}

    public static class DisjointSet{
        HashMap<Integer,Node> mp= new HashMap<>();

        public static class Node{
            int data;
            Node parent;
            int rank;
        }


        public void create(int val){
            Node nn= new Node();
            nn.data=val;
            nn.parent=nn;
            nn.rank=0;
            mp.put(val,nn);
        }

        public int find(int val){

            return findn(mp.get(val)).data;

        }


        public Node findn(Node n){
            if(n==n.parent){
                return n;
            }
            Node rr= findn(n.parent);
            n.parent=rr;
            return rr;
        }



        public void union(int val1, int val2){                                                                               // can also be used to check cycles

            Node n1= findn(mp.get(val1));
            Node n2= findn(mp.get(val2));


            if(n1.data==n2.data) {
                return;
            }



            if(n1.rank<n2.rank){
                n1.parent=n2;
            }

            else if(n2.rank<n1.rank){
                n2.parent=n1;
            }

            else {
                n2.parent=n1;
                n1.rank++;
            }

        }
    }









    public static void main(String[] args)  throws IOException {
        Reader.init(System.in);
        BufferedWriter out = new BufferedWriter(new OutputStreamWriter(System.out));
        int n= Reader.nextInt();
        int p= Reader.nextInt();
        int arr[][]= new int[n][2];
        long den=1;
        for (int i = 0; i <n ; i++) {
            arr[i][0]= Reader.nextInt();
            arr[i][1]= Reader.nextInt();
           // System.out.println(countDivisibles(arr[i][0],arr[i][1],p));
            den=den*(arr[i][1]-arr[i][0]+1);
        }
        int a[][]= new int[n+2][2];
        a[0][0]=arr[n-1][0];
        a[0][1]= arr[n-1][1];
        a[n+1][0]= arr[0][0];
        a[n+1][1]= arr[0][1];
        for (int i = 1; i <n+1 ; i++) {
            a[i][0]=arr[i-1][0];
            a[i][1]=arr[i-1][1];
        }

        double ar[]= new double[n+2];
        for (int i = 0; i <n+2 ; i++) {
            int l= a[i][0];
            int r= a[i][1];
          //  System.out.println("l="+l+"r="+r);
            ar[i]=(1.0*(r-l+1-countDivisibles(l,r,p))/(1.0*(r-l+1)));
         //   System.out.println(ar[i]);
        }


        double ans=0;
        for (int i = 1; i <n+1 ; i++) {
            double x1= ar[i-1];
            double x2= ar[i];
            ans+=2000*(1-x1*x2);
           // ans+=2000*(x1 + x2 - x1*x2);


        }
//        System.out.println(ans);

        System.out.println(ans);



















out.flush();
        out.close();

    }
    static int countDivisibles(int A, int B, int M)
    {
        // Add 1 explicitly as A is divisible by M
        if (A % M == 0)
            return (B / M) - (A / M) + 1;

        // A is not divisible by M
        return (B / M) - (A / M);
    }


    public static void df(int x, int y,int n, int m, char[][]ar, int l){
        boolean done[][]= new boolean[n][m];
        int count=0;
        LinkedList<int[]> stk= new LinkedList<>();
        int a[]= {x,y};
        stk.addFirst(a);
        while(!stk.isEmpty() && count<l){
          //  count++;
            int b[]=stk.removeFirst();
            if( done[b[0]][b[1]]){
                continue;
            }
            count++;

            done[b[0]][b[1]]=true;
            ar[b[0]][b[1]]='@';
            int arr[][]={{1,0},{-1,0},{0,1},{0,-1}};
            for (int i = 0; i <arr.length ; i++) {
                if(!(b[0]+arr[i][0]>=n || b[1]+arr[i][1]>=m || b[0]+arr[i][0]<0 || b[1]+arr[i][1]<0 ||  ar[b[0]+arr[i][0]][b[1]+arr[i][1]]=='#')){
                    int r[]= {b[0]+arr[i][0], b[1]+arr[i][1]};
                    stk.addFirst(r);
                   // continue;



            }
        }}


        for (int i = 0; i <n ; i++) {
            for (int j = 0; j <m ; j++) {
                if(ar[i][j]=='.'){
                    System.out.print('X');
                }
                else if(ar[i][j]=='@'){
                    System.out.print('.');
                }
                else{
                    System.out.print(ar[i][j]);
                }
            }
            System.out.println();
        }
























    }











    static long gcd(long a, long b)
    {
        if (a == 0)
            return b;
        return gcd(b % a, a);
    }



    static long gcd1(long a, long b)
    {

        // Everything divides 0
        if (a == 0)
            return b;
        if (b == 0)
            return a;

        // base case
        if (a == b)
            return a;

        // a is greater
        //count++;
        if (a > b){
            return gcd(a-b, b);

        }
        return gcd(a, b-a);
    }





    // method to return LCM of two numbers
    static long lcm(long a, long b)
    {
        return (a*b)/gcd(a, b);
    }

    // Driver method

    static int partition(long arr[],long arr1[], int low, int high)
    {
        long pivot = arr[high];
        int i = (low-1); // index of smaller element
        for (int j=low; j<high; j++)
        {
            // If current element is smaller than the pivot
            if (arr[j] < pivot)
            {
                i++;

                // swap arr[i] and arr[j]
                long temp = arr[i];
                arr[i] = arr[j];
                arr[j] = temp;
                long temp1=arr1[i];
                arr1[i]=arr1[j];
                arr1[j]=temp1;

            }
        }

        // swap arr[i+1] and arr[high] (or pivot)
        long temp = arr[i+1];
        arr[i+1] = arr[high];
        arr[high] = temp;
        long temp1= arr1[i+1];
        arr1[i+1]=arr1[high];
        arr1[high]= temp1;

        return i+1;
    }


    /* The main function that implements QuickSort()
      arr[] --> Array to be sorted,
      low  --> Starting index,
      high  --> Ending index */
    static void sort(long arr[],long arr1[], int low, int high)
    {
        if (low < high)
        {
            /* pi is partitioning index, arr[pi] is
              now at right place */
            int pi = partition(arr,arr1, low, high);

            // Recursively sort elements before
            // partition and after partition
            sort(arr,arr1, low, pi-1);
            sort(arr,arr1, pi+1, high);
        }
    }







































































    public static ArrayList<Integer> Sieve(int n) {
        boolean arr[]= new boolean [n+1];
        Arrays.fill(arr,true);
        arr[0]=false;
        arr[1]=false;
        for (int i = 2; i*i <=n ; i++) {
            if(arr[i]){
                for (int j = 2; j <=n/i ; j++) {
                    int u= i*j;
                    arr[u]=false;
                }}
        }
        ArrayList<Integer> ans= new ArrayList<>();
        for (int i = 0; i <n+1 ; i++) {
            if(arr[i]){
                ans.add(i);
            }
        }
        return ans;










    }





}