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.math.BigInteger;
import java.security.KeyStore;
import java.util.*;


public class A {

    long b = 31;
    String fileName = "";


    //////////////////////    SOLUTION   SOLUTION  SOLUTION    //////////////////////////////
    class Elem {
        int num, a, b;
        Elem(int num, int a, int b){
            this.num = num;
            this.a = a;
            this.b = b;
        }
    }
    int INF = Integer.MAX_VALUE;
    long MODULO = 1000*1000*1000+7;
    void solve() throws IOException {
        long n = readInt();
        long m = readInt();
        long ans = 0;
        ans += (n/5)*(m/5);
        ans += (n+1)/5*((m+4)/5);
        ans += (n+2)/5*((m+3)/5);
        ans += (n+3)/5*((m+2)/5);
        ans += (n+4)/5*((m+1)/5);
        out.println(ans);
    }

    class Pair implements Comparable<Pair>{
        int a, b;
        Pair(int a, int b){
            this.a = a;
            this.b = b;
        }

        @Override
        public int compareTo(Pair o) {

            return -Long.compare(Math.max(this.a - this.b, 0), Math.max(o.a - o.b, 0));
        }
    }
    ///////////////////////////////////////////////////////////////////////////////////////////

    class SparseTable{
        int[][] rmq;
        int[] logTable;
        int n;
        SparseTable(int[] a){
            n = a.length;
            logTable = new int[n+1];
            for(int i = 2; i <= n; ++i){
                logTable[i] = logTable[i >> 1] + 1;
            }
            rmq = new int[logTable[n] + 1][n];
            for(int i=0; i<n; ++i){
                rmq[0][i] = a[i];
            }

            for(int k=1; (1 << k) < n; ++k){
                for(int i=0; i + (1 << k) <= n; ++i){
                    int max1 = rmq[k - 1][i];
                    int max2 = rmq[k-1][i + (1 << (k-1))];
                    rmq[k][i] = Math.max(max1, max2);
                }
            }
        }

        int max(int l, int r){
            int k = logTable[r - l];
            int max1 = rmq[k][l];
            int max2 = rmq[k][r - (1 << k) + 1];
            return Math.max(max1, max2);
        }
    }
    long checkBit(long mask, int bit){
        return (mask >> bit) & 1;
    }
    class Dsu{
        int[] parent;
        int countSets;
        Dsu(int n){
            countSets = n;
            parent = new int[n];
            for(int i=0; i<n; ++i){
                parent[i] = i;
            }
        }
        int findSet(int a){
            if(parent[a] == a) return a;
            parent[a] = findSet(parent[a]);
            return parent[a];
        }
        void unionSets(int a, int b){
            a = findSet(a);
            b = findSet(b);
            if(a!=b){
                countSets--;
                parent[a] = b;
            }
        }
    }
    static int checkBit(int mask, int bit) {
        return (mask >> bit) & 1;
    }
    boolean isLower(char c){
        return c >= 'a' && c <= 'z';
    }

    ////////////////////////////////////////////////////////////

    class SegmentTree{
        int[] t;
        int n;
        SegmentTree(int n){
            t = new int[4*n];
            build(new int[n+1], 1, 1, n);
        }
        void build (int a[], int v, int tl, int tr) {
            if (tl == tr)
                t[v] = a[tl];
            else {
                int tm = (tl + tr) / 2;
                build (a, v*2, tl, tm);
                build (a, v*2+1, tm+1, tr);
            }
        }

        void update (int v, int tl, int tr, int l, int r, int add) {
            if (l > r)
                return;
            if (l == tl && tr == r)
                t[v] += add;
            else {
                int tm = (tl + tr) / 2;
                update (v*2, tl, tm, l, Math.min(r,tm), add);
                update (v*2+1, tm+1, tr, Math.max(l,tm+1), r, add);
            }
        }

        int get (int v, int tl, int tr, int pos) {
            if (tl == tr)
                return t[v];
            int tm = (tl + tr) / 2;
            if (pos <= tm)
                return t[v] + get (v*2, tl, tm, pos);
            else
                return t[v] + get (v*2+1, tm+1, tr, pos);
        }
    }
    class Fenwik {
        long[] t;
        int length;

        Fenwik(int[] a) {
            length = a.length + 100;
            t = new long[length];

            for (int i = 0; i < a.length; ++i) {
                inc(i, a[i]);
            }
        }

        void inc(int ind, int delta) {
            for (; ind < length; ind = ind | (ind + 1)) {
                t[ind] += delta;
            }
        }

        long getSum(int r) {
            long sum = 0;
            for (; r >= 0; r = (r & (r + 1)) - 1) {
                sum += t[r];
            }
            return sum;
        }
    }
    int gcd(int a, int b){
        return b == 0 ? a : gcd(b, a%b);
    }

    long binPow(long a, long b, long m) {
        if (b == 0) {
            return 1;
        }
        if (b % 2 == 1) {
            return ((a % m) * (binPow(a, b - 1, m) % m)) % m;
        } else {
            long c = binPow(a, b / 2, m);
            return (c * c) % m;
        }

    }
    int minInt(int... values) {
        int min = Integer.MAX_VALUE;
        for (int value : values) min = Math.min(min, value);
        return min;
    }

    int maxInt(int... values) {
        int max = Integer.MIN_VALUE;
        for (int value : values) max = Math.max(max, value);
        return max;
    }
    public static void main(String[] args) throws NumberFormatException, IOException {
        // TODO Auto-generated method stub
        new A().run();
    }

    void run() throws NumberFormatException, IOException {
        solve();
        out.close();
    };

    BufferedReader in;
    PrintWriter out;

    StringTokenizer tok;
    String delim = " ";
    Random rnd = new Random();

    A() throws FileNotFoundException {
        try {
            in = new BufferedReader(new FileReader("input.txt"));
            out = new PrintWriter("output.txt");
        } catch (Exception e) {
            if (fileName.isEmpty()) {
                in = new BufferedReader(new InputStreamReader(System.in));
                out = new PrintWriter(System.out);
            } else {
                in = new BufferedReader(new FileReader(fileName + ".in"));
                out = new PrintWriter(fileName + ".out");
            }

        }
        tok = new StringTokenizer("");
    }

    String readLine() throws IOException {
        return in.readLine();
    }

    String readString() throws IOException {
        while (!tok.hasMoreTokens()) {
            String nextLine = readLine();
            if (null == nextLine) {
                return null;
            }

            tok = new StringTokenizer(nextLine);
        }
        return tok.nextToken();
    }

    int readInt() throws NumberFormatException, IOException {
        return Integer.parseInt(readString());
    }
    byte readByte() throws NumberFormatException, IOException {
        return Byte.parseByte(readString());
    }
    int[] readIntArray (int n) throws NumberFormatException, IOException {
        int[] a = new int[n];
        for(int i=0; i<n; ++i){
            a[i] = readInt();
        }
        return a;
    }

    Integer[] readIntegerArray (int n) throws NumberFormatException, IOException {
        Integer[] a = new Integer[n];
        for(int i=0; i<n; ++i){
            a[i] = readInt();
        }
        return a;
    }

    long readLong() throws NumberFormatException, IOException {
        return Long.parseLong(readString());
    }

    double readDouble() throws NumberFormatException, IOException {
        return Double.parseDouble(readString());
    }
}


