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.util.*;
import java.util.Map.Entry;

import static java.lang.Math.*;

public class Main {

	public static void solve(FastScanner fscan, BufferedWriter bw) throws IOException {
		long n = fscan.nextInt(),
			m = fscan.nextInt();
		
		long ans = (n/5) * (m/5) + 
				 (n/5 + (n%5 >= 1? 1 : 0)) * (m/5 + (m%5 >= 4? 1 : 0)) +
				 (n/5 + (n%5 >= 2? 1 : 0)) * (m/5 + (m%5 >= 3? 1 : 0)) +
				 (n/5 + (n%5 >= 3? 1 : 0)) * (m/5 + (m%5 >= 2? 1 : 0)) +
				 (n/5 + (n%5 >= 4? 1 : 0)) * (m/5 + (m%5 >= 1? 1 : 0));
		
		bw.append(String.valueOf(ans));

	}
	

	/**************** ENTER HERE   ********************/
	public static void main(String[] args) throws Exception {
		
		if(args.length != 0){
			test();
			return;
		}
		
		FastScanner fscan = new FastScanner(System.in);
		BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(System.out));
		solve(fscan,bw);
		bw.close();
	}
	
	/****   Test Static test cases      **/
	public static void test() throws IOException{
		String testcase[] = new String[]{};
		String answer[] = new String[]{};
		
		for (int i = 0; i < testcase.length; i++) {
			ByteArrayOutputStream result = new ByteArrayOutputStream();
			FastScanner fscan = new FastScanner(new ByteArrayInputStream(testcase[i].getBytes()));
			BufferedWriter bw = new BufferedWriter(new OutputStreamWriter(result));
			
			solve(fscan, bw);
			
			String r = new String(result.toByteArray());
			if(! r.equals(answer[i])){
				String q = testcase[i];
				String a = answer[i];

				System.err.println("Wrong Answer on test:"+(i+1));
				System.err.println("Q:"+q);
				System.err.println("A:"+a);
				System.err.println("R:"+r);
			}
			
		}

	}
}






class IO {
	public static void readIntArray(int a[], int N, FastScanner fscan)
			throws IOException {
		readIntArray(a, N, 0, fscan);
	}

	public static void readIntArray(int a[], int N, int start, FastScanner fscan)
			throws IOException {
		for (int i = 0; i < N; i++) {
			a[start + i] = fscan.nextInt();
		}
	}

	public static void readArray(long a[], int N, FastScanner fscan)
			throws IOException {
		readArray(a, N, 0, fscan);
	}

	public static void readArray(long a[], int N, int start, FastScanner fscan)
			throws IOException {
		for (int i = 0; i < N; i++) {
			a[start + i] = fscan.nextInt();
		}
	}
}

class FastScanner {
	InputStream is;
	byte buff[] = new byte[1024];
	int currentChar = -1;
	int buffChars = 0;

	public FastScanner(InputStream inputStream) {
		is = inputStream;
	}

	public boolean hasNext() throws IOException {
		return currentChar == -1 || buffChars > 0;
	}

	public char nextChar() throws IOException {
		// if we already have that next char read, just return else input
		if (currentChar == -1 || currentChar >= buffChars) {
			currentChar = 0;
			buffChars = is.read(buff);
		}

		if (buffChars <= 0) {
			throw new RuntimeException("No char found...");
		}

		int ch;
		while (isSpace(ch = nextCharAsInt()))
			;
		return (char) ch;
	}

	public int nextCharAsInt() throws IOException {
		// if we already have that next char read, just return else input
		if (currentChar == -1 || currentChar >= buffChars) {
			currentChar = 0;
			buffChars = is.read(buff);
		}

		if (buffChars <= 0) {
			return -1;
		}
		return (char) buff[currentChar++];
	}

	public String nextLine() throws IOException {
		StringBuilder bldr = new StringBuilder();
		int ch;
		while (isLineEnd(ch = nextCharAsInt()))
			// ignore empty lines ???
			;

		do {
			bldr.append((char) ch);
		} while (!isLineEnd(ch = nextCharAsInt()));

		return bldr.toString();
	}

	public String nextString() throws IOException {
		StringBuilder bldr = new StringBuilder();
		int ch;
		while (isSpace(ch = nextCharAsInt()))
			;

		do {
			bldr.append((char) ch);
		} while (!isSpace(ch = nextCharAsInt()));

		return bldr.toString();
	}

	public int nextInt() throws IOException {
		// considering ASCII files--> 8 bit chars, unicode files has 16 bit
		// chars (byte1 then byte2)
		int result = 0;
		int sign = 1;
		int ch;
		while (isSpace(ch = nextCharAsInt()))
			;

		if (ch == '-') {
			sign = -1;
			ch = nextCharAsInt();
		}

		do {
			if (ch < '0' || ch > '9')
				throw new NumberFormatException("Found '" + ch
						+ "' while parsing for int.");

			result *= 10;
			result += ch - '0';
		} while (!isSpace(ch = nextCharAsInt()));

		return sign * result;
	}

	public long nextLong() throws IOException {
		// considering ASCII files--> 8 bit chars, unicode files has 16 bit
		// chars (byte1 then byte2)
		long result = 0;
		int sign = 1;
		int ch;
		while (isSpace(ch = nextCharAsInt()))
			;

		if (ch == '-') {
			sign = -1;
			ch = nextCharAsInt();
		}

		do {
			if (ch < '0' || ch > '9')
				throw new NumberFormatException("Found '" + ch
						+ "' while parsing for int.");

			result *= 10;
			result += ch - '0';
		} while (!isSpace(ch = nextCharAsInt()));

		return sign * result;
	}

	private boolean isLineEnd(int ch) {
		return ch == '\n' || ch == '\r' || ch == -1;
	}

	private boolean isSpace(int ch) {
		return ch == '\n' || ch == ' ' || ch == '\t' || ch == '\r' || ch == -1;
	}

	public void close() throws IOException {
		is.close();
	}
}
