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.
// All important imports 
import static java.lang.System.in;

import java.io.BufferedReader;
import java.io.ByteArrayInputStream;
import java.io.DataInputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.lang.reflect.Array;
import java.math.BigInteger;
import java.text.DecimalFormat;
import java.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Collections;
import java.util.Comparator;
import java.util.Date;
import java.util.Deque;
import java.util.GregorianCalendar;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Hashtable;
import java.util.InputMismatchException;
import java.util.LinkedList;
import java.util.List;
import java.util.Map;
import java.util.PriorityQueue;
import java.util.Stack;
import java.util.Queue;
import java.util.Random;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.Vector;

public class Main{

	public static void solve(){
		int m =ni();
		int n = ni();
		long sum=0;
		int s=2;
		int e=n+1;
		for(int i=1;i<=m;i++){
			sum = sum + e/5 -(s-1)/5;
			s++;
			e++;
		
		}
		out.println(sum);
	}
	
	
    
        // END OF SOLUTION
        // INPUT OUTPUT TEMPLATE
        static String TESTCASES;
        static PrintWriter out;

        
    public static void main(String[] args) throws Exception,IOException{
                out=new PrintWriter(System.out);
                InputStream myinp=System.in;
                init(myinp);
//                int t=ni();
//                int i=1;
//                while(t-->0)
                {solve();}
                out.close();
                
                  }
        
    
        static InputStream is;
        static BufferedReader brr;
        static int BUFFER_SIZE = 65000;
        static DataInputStream din;
        static byte[] buffer;
        static int bufferPointer, bytesRead;
        public static void init(InputStream input) {
        is=input;
        brr=new BufferedReader(new InputStreamReader(input));
        din = new DataInputStream(in);
        buffer = new byte[BUFFER_SIZE];
        bufferPointer = bytesRead = 0;
        }
        
    
    protected static byte[] inbuf = new byte[1024];
    static int lenbuf = 0, ptrbuf = 0;
    
        static byte read() throws Exception
        {
            if (bufferPointer == bytesRead) fillBuffer();
            return buffer[bufferPointer++];
        }
        
    protected static int readByte()
    {
        if(lenbuf == -1)throw new InputMismatchException();
        if(ptrbuf >= lenbuf){
            ptrbuf = 0;
            try { lenbuf = is.read(inbuf); } catch (IOException e) { throw new InputMismatchException(); }
            if(lenbuf <= 0)return -1;
        }
        return inbuf[ptrbuf++];
    }
        
        protected static String readline() throws IOException
        {
            return brr.readLine();
        }
                
    
    
    // extras
    protected static double nd() { return Double.parseDouble(ns()); }
    protected static char nc() { return (char)skip(); }
    protected static boolean isSpaceChar(int c) { return !(c >= 33 && c <= 126); }
    protected static int skip() { 
            int b; while((b = readByte()) != -1 && isSpaceChar(b)); return b; 
        }
        static void fillBuffer() throws Exception
        {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1) buffer[0] = -1;
        }
        
    protected static String ns()
    {
        int b = skip();
        StringBuilder sb = new StringBuilder();
        while(!(isSpaceChar(b))){ // when nextLine, (isSpaceChar(b) && b != ' ')
            sb.appendCodePoint(b);
            b = readByte();
        }
        return sb.toString();
    }
    
    protected static char[] nca(int n)
    {
        char[] buf = new char[n];
        int b = skip(), p = 0;
        while(p < n && !(isSpaceChar(b))){
            buf[p++] = (char)b;
            b = readByte();
        }
        return n == p ? buf : Arrays.copyOf(buf, p);
    }
    
    
    protected static int[] nia(int n)
    {
        int[] a = new int[n];
        for(int i = 0;i < n;i++)a[i] = ni();
        return a;
    }
        
        protected static int[][] niaindex(int n)
        {
                int ea[][]=new int[n][2];
                for(int i=0;i<n;i++)
                {
                    ea[i][0]=ni();
                    ea[i][1]=i;
                }
                return ea;
        }
        
        protected static long[] nla(int n)
    {
        long[] a = new long[n];
        for(int i = 0;i < n;i++)a[i] = nl();
        return a;
    }
        
        protected static long[][] nlaindex(int n)
        {
                long ea[][]=new long[n][2];
                for(int i=0;i<n;i++)
                {
                    ea[i][0]=ni();
                    ea[i][1]=i;
                }
                return ea;
        }
        
        protected static String[] nsa(int n)
    {
        String[] a = new String[n];
        for(int i = 0;i < n;i++)a[i] = ns();
        return a;
    }
        
        protected static double[] nda(int n)
    {
        double[] a = new double[n];
        for(int i = 0;i < n;i++)a[i] = nd();
        return a;
    }
    
        static int ni2() throws Exception
        {
            int ret = 0;
            byte c = read();
            while (c <= ' ') c = read();
            boolean neg = c == '-';
            if (neg) c = read();
            do
            {
                ret = ret * 10 + c - '0';
                c = read();
            } while (c > ' ');
            if (neg) return -ret;
            return ret;
 
        }
        
        
 
    
        
    protected static int ni()
    {
        int num = 0, b;
        boolean minus = false;
        while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        
        while(true){
            if(b >= '0' && b <= '9'){
                num = num * 10 + (b - '0');
            }else{
                return minus ? -num : num;
            }
            b = readByte();
        }
    }
        
    
    protected static long nl()
    {
        long num = 0;
        int b;
        boolean minus = false;
        while((b = readByte()) != -1 && !((b >= '0' && b <= '9') || b == '-'));
        if(b == '-'){
            minus = true;
            b = readByte();
        }
        
        while(true){
            if(b >= '0' && b <= '9'){
                num = num * 10 + (b - '0');
            }else{
                return minus ? -num : num;
            }
            b = readByte();
        }
    }
        
        
        // Outputs
        public static void pln(){out.println();}
        public static void ps(String s){out.print(s);}
        public static void pi(int s){out.print(s);}
        public static void pl(long s){out.print(s);}
        public static void pd(double s){out.print(s);}
        public static void psp(){out.print(" ");}
        public static void parr(int s[]){out.println(Arrays.toString(s));}
        public static void parr(String s[]){out.println(Arrays.toString(s));}
        public static void parr(long s[]){out.println(Arrays.toString(s));}        
        public static void parr2(int s[][]){for(int i=0;i<s.length;i++)out.println(Arrays.toString(s[i]));}
        public static void parr2(long s[][]){for(int i=0;i<s.length;i++)out.println(Arrays.toString(s[i]));}
        public static void parr2(String s[][]){for(int i=0;i<s.length;i++)out.println(Arrays.toString(s[i]));}
 
}