Recently a serious bug has been found in the FOS code. The head of the F company wants to find the culprit and punish him. For that, he set up an organizational meeting, the issue is: who's bugged the code? Each of the n coders on the meeting said: 'I know for sure that either x or y did it!'

The head of the company decided to choose two suspects and invite them to his office. Naturally, he should consider the coders' opinions. That's why the head wants to make such a choice that at least p of n coders agreed with it. A coder agrees with the choice of two suspects if at least one of the two people that he named at the meeting was chosen as a suspect. In how many ways can the head of F choose two suspects?

Note that even if some coder was chosen as a suspect, he can agree with the head's choice if he named the other chosen coder at the meeting.

Input

The first line contains integers n and p (3 ≤ n ≤ 3·105; 0 ≤ p ≤ n) — the number of coders in the F company and the minimum number of agreed people.

Each of the next n lines contains two integers xi, yi (1 ≤ xi, yi ≤ n) — the numbers of coders named by the i-th coder. It is guaranteed that xi ≠ i, yi ≠ i, xi ≠ yi.

Output

Print a single integer –– the number of possible two-suspect sets. Note that the order of the suspects doesn't matter, that is, sets (1, 2) и (2, 1) are considered identical.

Examples

Input

4 2
2 3
1 4
1 4
2 1


Output

6


Input

8 6
5 6
5 7
5 8
6 2
2 1
7 3
1 3
1 4


Output

1
import java.util.Map;
import java.io.IOException;
import java.util.Arrays;
import java.util.TreeMap;
import java.util.ArrayList;
import java.util.Set;
import java.util.Comparator;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.io.Writer;
import java.math.BigInteger;
import java.io.InputStream;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 * @author Shamir14 (amirhossein.shapoori@gmail.com)
 */
public class Main {
	public static void main(String[] args) {
		InputStream inputStream = System.in;
		OutputStream outputStream = System.out;
		InputReader in = new InputReader(inputStream);
		OutputWriter out = new OutputWriter(outputStream);
		TaskCC solver = new TaskCC();
		solver.solve(1, in, out);
		out.close();
	}
}

class TaskCC {
    public void solve(int testNumber, InputReader in, OutputWriter out) {
        int n = in.readInt();
        int p = in.readInt();
        ArrayList<Integer>[] adj = new ArrayList[n];
        for (int i = 0; i < n; i++) {
            adj[i] = new ArrayList<Integer>();
        }
        TreeMap<Pair, Integer> CM = new TreeMap<Pair, Integer>();

        int deg[] = new int[n];
        for (int i = 0; i < n; i++) {
            int sus1 = in.readInt() - 1;
            int sus2 = in.readInt() - 1;

            adj[sus1].add(i);
            deg[sus1]++;
            adj[sus2].add(i);
            deg[sus2]++;
            if(sus1 > sus2) {
                int temp = sus1;
                sus1 = sus2;
                sus2 = temp;
            }
            Pair pair = new Pair(sus1, sus2);
            int val = CM.get(pair) == null ? 0 : CM.get(pair);
            CM.put(pair, val+1);
        }

        int order[] = IntArrays.getOrder(deg);
        int cnt = 0;
        long ans = 0;
        for (int i : order) {
            int need = p - deg[i];
            int where = IntArrays.lowerBound(order, deg, need);
            ans += n - where;
            if(cnt >= where)
                ans--;
            cnt++;
        }
        for (Map.Entry<Pair, Integer> entry : CM.entrySet()) {
            if(deg[entry.getKey().x] + deg[entry.getKey().y] >= p) {
                ans-=2;
                if(deg[entry.getKey().x] + deg[entry.getKey().y] - entry.getValue() >= p)
                    ans+=2;
            }
        }

        if(ans%2 != 0)
            throw new UnknownError();

        out.printLine(ans / 2);

    }




}

class InputReader {
    // this IO reading - writing is provided by Egor Kulikov
    private InputStream stream;
    private byte[] buf = new byte[1024];
    private int curChar;
    private int numChars;

    public InputReader(InputStream stream) {
        this.stream = stream;
    }

    public int read() {
        if (numChars == -1)
            throw new UnknownError();
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                throw new UnknownError();
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar++];
    }


    public boolean hasNext(){
        return peek()!=-1;
    }

    public int peek() {
        if (numChars == -1)
            return -1;
        if (curChar >= numChars) {
            curChar = 0;
            try {
                numChars = stream.read(buf);
            } catch (IOException e) {
                return -1;
            }
            if (numChars <= 0)
                return -1;
        }
        return buf[curChar];
    }

    public int readInt() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        int res = 0;
        do {
            if (c < '0' || c > '9')
                throw new UnknownError();
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }

    public long readLong() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        long res = 0;
        do {
            if (c < '0' || c > '9')
                throw new UnknownError();
            res *= 10;
            res += c - '0';
            c = read();
        } while (!isSpaceChar(c));
        return res * sgn;
    }

    public String readString() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        StringBuffer res = new StringBuffer();
        do {
            res.appendCodePoint(c);
            c = read();
        } while (!isSpaceChar(c));
        return res.toString();
    }

    public static boolean isSpaceChar(int c) {
        return c == ' ' || c == '\n' || c == '\r' || c == '\t' || c == -1;
    }

    private String readLine0() {
        StringBuffer buf = new StringBuffer();
        int c = read();
        while (c != '\n' && c != -1) {
            if (c != '\r')
                buf.appendCodePoint(c);
            c = read();
        }
        return buf.toString();
    }

    public String readLine() {
        String s = readLine0();
        while (s.trim().length() == 0)
            s = readLine0();
        return s;
    }

    public String readLine(boolean ignoreEmptyLines) {
        if (ignoreEmptyLines)
            return readLine();
        else
            return readLine0();
    }

    public BigInteger readBigInteger() {
        try {
            return new BigInteger(readString());
        } catch (NumberFormatException e) {
            throw new UnknownError();
        }
    }

    public char readCharacter() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        return (char) c;
    }

    public double readDouble() {
        int c = read();
        while (isSpaceChar(c))
            c = read();
        int sgn = 1;
        if (c == '-') {
            sgn = -1;
            c = read();
        }
        double res = 0;
        while (!isSpaceChar(c) && c != '.') {
            if (c == 'e' || c == 'E')
                return res * Math.pow(10, readInt());
            if (c < '0' || c > '9')
                throw new UnknownError();
            res *= 10;
            res += c - '0';
            c = read();
        }
        if (c == '.') {
            c = read();
            double m = 1;
            while (!isSpaceChar(c)) {
                if (c == 'e' || c == 'E')
                    return res * Math.pow(10, readInt());
                if (c < '0' || c > '9')
                    throw new UnknownError();
                m /= 10;
                res += (c - '0') * m;
                c = read();
            }
        }
        return res * sgn;
    }

    public boolean isExhausted() {
        int value;
        while (isSpaceChar(value = peek()) && value != -1)
            read();
        return value == -1;
    }

    public String next() {
        return readString();
    }
}

class OutputWriter {
    private final PrintWriter writer;

    public OutputWriter(OutputStream outputStream) {
        writer = new PrintWriter(outputStream);
    }

    public OutputWriter(Writer writer) {
        this.writer = new PrintWriter(writer);
    }

    public void print(Object...objects) {
        for (int i = 0; i < objects.length; i++) {
            if (i != 0)
                writer.print(' ');
            writer.print(objects[i]);
        }
    }

    public void printLine(Object...objects) {
        print(objects);
        writer.println();
    }

    public void printLine(char[] array) {
        writer.println(array);
    }

    public void printFormat(String format, Object...objects) {
        writer.printf(format, objects);
    }

    public void close() {
        writer.close();
    }

    public void flush() {
        writer.flush();
    }
}

class Pair implements Comparable <Pair>{
    public int x, y;

    public Pair(int xx, int yy){
        x = xx;
        y = yy;
    }

    public Pair add(Pair a){
        return new Pair(x + a.x, y + a.y);
    }

    @Override
    public int compareTo(Pair o) {
        if(x!=o.x)
            return x - o.x;
        return y - o.y;
    }
}

class IntArrays{

    public static void reverse(int[] cur){
        int[] temp = new int[cur.length];
        int cnt = 0;
        for(int i=cur.length-1; i>=0; i--){
            temp[cnt++] = cur[i];
        }
        for(int i=0;i<cnt; i++)
            cur[i] = temp[i];
    }

    public static void swap(int[] arr, int a, int b){
        int temp = arr[a];
        arr[a] = arr[b];
        arr[b] = temp;
    }

    public static void print(int[] arr, OutputWriter out){
        boolean first = true;
        for(int temp: arr){
            if(first)
                first = false;
            else
                out.print(" ");
            out.print(temp);
        }
        out.printLine();
    }

    private static Integer[] selfOrder(int n) {
        Integer[] self = new Integer[n];
        for (int i = 0; i < n; i++) {
            self[i] = i;
        }
        return self;
    }

    public static int[] getOrder(final int[] arr) {
        Integer[] order = selfOrder(arr.length);
        Arrays.sort(order, new Comparator<Integer>() {
            @Override
            public int compare(Integer o1, Integer o2) {
                if(arr[o1] > arr[o2])
                    return 1;
                if(arr[o1] < arr[o2])
                    return -1;
                return 0;
            }
        });

        int[] Order = new int[arr.length];
        int cnt = 0;
        for (Integer integer : order) {
            Order[cnt++] = integer;
        }
        return Order;
    }

    public static boolean next_permutation(int[] c){
        // 1. finds the largest k, that c[k] < c[k+1]
        int first = getFirst( c );
        if ( first == -1 ) return false; // no greater permutation
        // 2. find last index toSwap, that c[k] < c[toSwap]
        int toSwap = c.length - 1;
        while ( c[ first ] >= c[ toSwap ] )
            --toSwap;
        // 3. swap elements with indexes first and last
        swap( c, first++, toSwap );
        // 4. reverse sequence from k+1 to n (inclusive)
        toSwap = c.length - 1;
        while ( first < toSwap )
            swap( c, first++, toSwap-- );
        return true;
    }

    // finds the largest k, that c[k] < c[k+1]
    // if no such k exists (there is not greater permutation), return -1
    private static int getFirst( final int[] c ) {
        for ( int i = c.length - 2; i >= 0; --i )
            if ( c[ i ] <  c[ i + 1 ] )
                return i;
        return -1;
    }

    /**
     * return the minimum index i such that val[ order[ i ] ] >= need
     */
    public static int lowerBound(int[] order, int[] val, int need) {
        int s = 0;
        int e = order.length;
        while(e - s > 1) {
            int mid = (e + s) / 2;
            if(val[order[mid]] < need)
                s = mid;
            else
                e = mid;
        }
        if(val[order[s]] >= need)
            return s;
        return e;
    }


}
