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.Arrays;

public class ProblemA {
  
  public static void main(String[] args) throws IOException {
    init();
    new ProblemA().run();
    out.flush();
    out.close();
  }
  
  static void init() throws IOException {
    in = new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
    out = new PrintWriter(new OutputStreamWriter(System.out));
    in.ordinaryChars(0, 65535);
    in.wordChars(0, 65535);
    in.whitespaceChars(' ', ' ');
    in.whitespaceChars('\n', '\n');
    in.whitespaceChars('\r', '\r');
  }
  
  // класс для пар
  class Pair<L, R> {
    private final L X;
    private final R Y;
    
    public Pair(L X, R Y) {
      this.X = X;
      this.Y = Y;
    }
    
    public L getX() {
      return X;
    }
    
    public R getY() {
      return Y;
    }
    
    @Override
    public int hashCode() {
      return X.hashCode() ^ Y.hashCode();
    }
    
    @Override
    public boolean equals(Object o) {
      if (!(o instanceof Pair)) return false;
      Pair pairo = (Pair) o;
      return X.equals(pairo.getX()) && Y.equals(pairo.getY());
    }
  }
  
  static final long INFL = 200000000000000000L;
  static final int INF = 2000000000;
  static final boolean DEBUG = true;
  
  static StreamTokenizer in;
  static PrintWriter out;
  
  static void print(String s) {
    print(s, 0);
  }
  
  static void print(String s, int debug) {
    if (debug == 0 || DEBUG) {
      out.print(s);
    }
  }
  
  static void println(String s) {
    println(s, 0);
  }
  
  static void println(String s, int debug) {
    if (debug == 0 || DEBUG) {
      out.println(s);
    }
  }
  
  static void printArray(int[] arr) {
    println(Arrays.toString(arr));
  }
  
  static void printArray(char[] arr) {
    println(Arrays.toString(arr));
  }
  
  static void printArray(String[] arr) {
    println(Arrays.toString(arr));
  }
  
  static char[] inChars;
  static int inCharsInd;
  
  static String next() throws IOException {
    in.nextToken();
    return in.sval;
  }
  
  static char nextChar() throws IOException {
    while (inChars == null || inCharsInd >= inChars.length) {
      inChars = next().toCharArray();
      inCharsInd = 0;
    }
    return inChars[inCharsInd++];
  }
  
  static int nextInt() throws IOException {
    return Integer.valueOf(next());
  }
  
  static double nextDouble() throws IOException {
    return Double.valueOf(next());
  }
  
  static long nextLong() throws IOException {
    return Long.valueOf(next());
  }
  
  private void run() throws IOException {
    solve();
  }
  
  int K, L, M, N, P;
  
  private void solve() throws IOException {
    N = nextInt();
    M = nextInt();
    long nmod = N%5, ndiv = N/5;
    long mmod = M%5, mdiv = M/5;
    int count = 0;
    for (int i = 1; i <= nmod; i++) {
      for (int j = 1; j <= mmod; j++) {
        if (i+j==5){
          count++;
        }
      }
    }
    out.println(5*ndiv*mdiv + nmod*mdiv + mmod*ndiv + count);
  }
  
}
