After finishing eating her bun, Alyona came up with two integers n and m. She decided to write down two columns of integers — the first column containing integers from 1 to n and the second containing integers from 1 to m. Now the girl wants to count how many pairs of integers she can choose, one from the first column and the other from the second column, such that their sum is divisible by 5.

Formally, Alyona wants to count the number of pairs of integers (x, y) such that 1 ≤ x ≤ n, 1 ≤ y ≤ m and <image> equals 0.

As usual, Alyona has some troubles and asks you to help.

Input

The only line of the input contains two integers n and m (1 ≤ n, m ≤ 1 000 000).

Output

Print the only integer — the number of pairs of integers (x, y) such that 1 ≤ x ≤ n, 1 ≤ y ≤ m and (x + y) is divisible by 5.

Examples

Input

6 12


Output

14


Input

11 14


Output

31


Input

1 5


Output

1


Input

3 8


Output

5


Input

5 7


Output

7


Input

21 21


Output

88

Note

Following pairs are suitable in the first sample case: 

  * for x = 1 fits y equal to 4 or 9; 
  * for x = 2 fits y equal to 3 or 8; 
  * for x = 3 fits y equal to 2, 7 or 12; 
  * for x = 4 fits y equal to 1, 6 or 11; 
  * for x = 5 fits y equal to 5 or 10; 
  * for x = 6 fits y equal to 4 or 9. 



Only the pair (1, 4) is suitable in the third sample case.
import java.io.*;
import java.util.*;
import java.util.stream.Collectors;

public class Solution {
    public static void main(String[] args) throws IOException {
        IO io = new IO() ;
        int n = io.getInt(), m = io.getInt();
        long sum = 0 ;
        int[] mlast = new int[5], nlast = new int[5] ;
        int[] mfirst = {5, 1, 2, 3, 4}, nfirst = mfirst ;

        for(int i = 0 ; i < 5 ; i++){
            nlast[(n - i + 5) % 5] = n - i ;
            mlast[(m - i + 5) % 5] = m - i ;
        }
        for(int i = 0 ; i < 5 ; i++){
            if(mlast[i] > 0)
                mlast[i] = (mlast[i] - mfirst[i]) / 5 + 1 ;
            if(nlast[i] > 0)
                nlast[i] = (nlast[i] - nfirst[i]) / 5 + 1 ;
        }
        for(int i = 0 ; i < 5 ; i++){
            int a = i, b = (5 - i) % 5 ;
            if(mlast[a] > 0 && nlast[b] > 0)
                sum += (long)mlast[a]*nlast[b] ;
        }
        Utils.print(sum) ;
    }
}

class Utils {

    public static void swap(List<Integer> ls, int i, int j){
        int temp = ls.get(i) ;
        ls.set(i, ls.get(j)) ;
        ls.set(j, temp) ;
    }

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

    public static long subSum(long[] pre, int l, int h){
        return l == 0 ? pre[h]: pre[h] - pre[l - 1] ;
    }

    public static class Pair implements Comparable<Pair>{
        public int m, s ;

        public Pair(int a, int b) {
            this.m = a;
            this.s = b;
        }

        @Override
        public int compareTo(Pair o) {
            return m - o.m ;
        }

        @Override
        public String toString() {
            return "Pair{" +
                    "m=" + m +
                    ", s=" + s +
                    '}';
        }
    }

    public static void ifPrint(boolean test, Object ifValue, Object elseValue){
        System.out.println(test ? ifValue: elseValue) ;
    }

    public static void print(Character delim, Object... a){
        List<String> top = new ArrayList<>() ;
        for(Object aa: a)
            top.add(aa == null ? "null": aa.toString()) ;
        System.out.println(join(top, delim.toString())) ;
    }

    public static void print(Object... a){
        print(' ', a) ;
    }

    public static  <T extends Comparable<T>> int lowerBound(T[] arr, int l, int h, T key){
        while(l < h){
            int mid = (l + h) / 2 ;
            if(arr[mid].compareTo(key) < 0)
                l = mid + 1 ;
            else
                h = mid ;
        }
        return arr[l].compareTo(key) >= 0 ? l: -1 ;
    }

    public static <T extends Comparable<T>> int upperBound(T[] arr, int l, int h, T key){
        while(l < h){
            int mid = (l + h) / 2 ;
            if(arr[mid].compareTo(key) < 0)
                l = mid + 1 ;
            else if(arr[mid].compareTo(key) == 0)
                l = mid ;
            else
                h = mid ;
            if(h == l + 1)
                break ;
        }
        return arr[l].compareTo(key) >= 0 ? l: -1 ;
    }

    public static class IndexedElement<T> {
        int idx;
        T val;

        public IndexedElement(int idx, T val) {
            this.idx = idx;
            this.val = val;
        }
    }

    public static <T> ArrayList<IndexedElement<T>> getIndexedArray(ArrayList<T> ip) {
        ArrayList<IndexedElement<T>> op = new ArrayList<>();
        for (int i = 0; i < ip.size(); i++) {
            op.add(new IndexedElement<>(i, ip.get(i)));
        }
        return op;
    }

    public static <T> String join(List<T> ls) {
        return join(ls, " ") ;
    }

    public static <T> String join(List<T> ls, String delim) {
        StringJoiner sj = new StringJoiner(delim);
        for (T a : ls)
            sj.add(a.toString());
        return sj.toString();
    }

    public static <T> void print2DArray(List<List<T>> mat) {
        for (List<T> m : mat) {
            System.out.println("{ " + join(m, ", ") + " }");
        }
    }

    public static  <T> void reverseArrray(T[] arr, int l, int h){
        while(l < h){
            T temp = arr[l] ;
            arr[l] = arr[h] ;
            arr[h] = temp ;
            l++ ;
            h-- ;
        }
    }
}

class IO {
    private BufferedReader br = null;
    private StringTokenizer st = null;

    public IO() {
        this(System.in);
    }

    public IO(InputStream is) {
        this.br = new BufferedReader(new InputStreamReader(is));
    }

    public List<String> getStringArray(int n) throws IOException {
        if (n == 0)
            return new ArrayList<>();
        if (st == null || !st.hasMoreTokens())
            st = new StringTokenizer(br.readLine());
        List<String> res = new ArrayList<>();
        for (int i = 0; i < n; i++) {
            if (!st.hasMoreTokens())
                st = new StringTokenizer(br.readLine());
            res.add(st.nextToken());
        }
        return res;
    }
    public String getString() throws IOException {
        List<String> res = this.getStringArray(1);
        return res.size() == 0 ? "" : res.get(0);
    }

    public List<Integer> getIntegerArray(int n) throws IOException {
        if (n == 0)
            return new ArrayList<>();
        List<String> res = getStringArray(n);
        return res.stream().map(Integer::parseInt).collect(Collectors.toList());
    }
    public Integer getInt() throws IOException {
        List<Integer> res = this.getIntegerArray(1);
        return res.size() == 0 ? 0 : res.get(0);
    }

    public List<Long> getLongArray(int n) throws IOException {
        if (n == 0)
            return new ArrayList<>();
        List<String> res = getStringArray(n);
        return res.stream().map(Long::parseLong).collect(Collectors.toList());
    }
    public Long getLong() throws IOException {
        List<Long> res = this.getLongArray(1);
        return res.size() == 0 ? 0L : res.get(0);
    }

    public List<Double> getDoubleArray(int n) throws IOException {
        if (n == 0)
            return new ArrayList<>();
        List<String> res = getStringArray(n);
        return res.stream().map(Double::parseDouble).collect(Collectors.toList());
    }
    public Double getDouble() throws IOException {
        List<Double> res = this.getDoubleArray(1);
        return res.size() == 0 ? 0.0 : res.get(0);
    }
}