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.util.*;
import java.io.*;
import java.math.BigDecimal;
import java.math.BigInteger;
import static java.lang.Math.*;
import static java.util.Arrays.*;
import static java.util.Collections.*;



/*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ CONTROLLER CLASS   ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
/*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/


public class Main {
	public static void main(String[] args) throws Exception {
		InputReader in = new InputReader(System.in);
		PrintWriter out = new PrintWriter(System.out);
		TaskA solver = new TaskA();
		solver.solve(1, in, out);
		out.close();
	}

static class TaskA {
	

	
/*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ OTHER USEFULL METHODS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
/*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
		// GCD && LCM
		long gcd(long a, long b) {
			return b == 0 ? a : gcd(b, a % b);
		}

		long lcm(long a, long b) {
			return a * (b / gcd(a, b));
		}

		// REverse a String
		String rev(String s) {
			return new StringBuilder(s).reverse().toString();
		}


/*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
/*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ SOLUTION  IS RIGHT HERE^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
/*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
	
	
		public void solve(int testNumber, InputReader in, PrintWriter out) throws IOException {
			// BufferedReader br = new BufferedReader(new
			// InputStreamReader(System.in));
			// Scanner sc = new Scanner(System.in);
			int n = in.nextInt() , m = in.nextInt();
			long[] one = new long[5];
			long[] two = new long[5];
			
			for(int i = 1; i <= n; i++ )
				one[i%5]++;
			for(int i = 1; i <= m; i++ )
				two[i%5]++;
			one[0] = one[0] * two[0];
			one[1] = one[1] * two[4]; 
			one[2] = one[2] * two[3];
			one[3] = one[3] * two[2];
			one[4] = one[4] * two[1];
			out.println(one[0]+one[1]+one[2]+one[3]+one[4]);
		}
	}

 /*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
 /*^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^ INPUT READER CLASS ^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^^*/
 /*``````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````````*/
	


    static class InputReader {
		private byte[] buf = new byte[8000];
		private int index;
		private int total;
		private InputStream in;
		//BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		public InputReader(InputStream stream) {
			in = stream;
		}

		public int scan() {
			if (total == -1)
				throw new InputMismatchException();
			if (index >= total) {
				index = 0;
				try {
					total = in.read(buf);
				} catch (IOException e) {
					throw new InputMismatchException();
				}
				if (total <= 0)
					return -1;
			}
			return buf[index++];
		}

		public long scanlong() {
			long integer = 0;
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			int neg = 1;
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n)) {
				if (n >= '0' && n <= '9') {
					integer *= 10;
					integer += n - '0';
					n = scan();
				} else
					throw new InputMismatchException();
			}
			return neg * integer;
		}

		private int scanInt() {
			int integer = 0;
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			int neg = 1;
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n)) {
				if (n >= '0' && n <= '9') {
					integer *= 10;
					integer += n - '0';
					n = scan();
				} else
					throw new InputMismatchException();
			}
			return neg * integer;
		}

		public double scandouble() {
			double doubll = 0;
			int n = scan();
			int neg = 1;
			while (isWhiteSpace(n))
				n = scan();
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n) && n != '.') {
				if (n >= '0' && n <= '9') {
					doubll *= 10;
					doubll += n - '0';
					n = scan();
				}
			}
			if (n == '.') {
				n = scan();
				double temp = 1;
				while (!isWhiteSpace(n)) {
					if (n >= '0' && n <= '9') {
						temp /= 10;
						doubll += (n - '0') * temp;
						n = scan();
					}
				}
			}
			return neg * doubll;
		}

		private float scanfloat() {
			float doubll = 0;
			int n = scan();
			int neg = 1;
			while (isWhiteSpace(n))
				n = scan();
			if (n == '-') {
				neg = -1;
				n = scan();
			}
			while (!isWhiteSpace(n) && n != '.') {
				if (n >= '0' && n <= '9') {
					doubll *= 10;
					doubll += n - '0';
					n = scan();
				}
			}
			if (n == '.') {
				n = scan();
				double temp = 1;
				while (!isWhiteSpace(n)) {
					if (n >= '0' && n <= '9') {
						temp /= 10;
						doubll += (n - '0') * temp;
						n = scan();
					}
				}
			}
			return neg * doubll;
		}

		public String scanstring() {
			StringBuilder sb = new StringBuilder();
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			while (!isWhiteSpace(n)) {
				sb.append((char) n);
				n = scan();
			}
			return sb.toString();
		}

		public String scan_nextLine() {
			int n = scan();
			while (isWhiteSpace(n))
				n = scan();
			StringBuilder res = new StringBuilder();
			do {
				res.appendCodePoint(n);
				n = scan();
			} while (!isEndOfLine(n));
			return res.toString();
		}

		public boolean isWhiteSpace(int n) {
			if (n == ' ' || n == '\n' || n == '\r' || n == '\t' || n == -1)
				return true;
			return false;
		}

		private boolean isEndOfLine(int c) {
			return c == '\n' || c == '\r' || c == -1;
		}
		/// Input module

		public int nextInt() {
			return scanInt();
		}

		public long nextLong() {
			return scanlong();
		}

		public double nextDouble() {
			return scandouble();
		}

		public float nextFloat() {
			return scanfloat();
		}

		public String next() {
			return scanstring();
		}

		public String nextLine() throws IOException {
			return scan_nextLine();
		}

		public int[] readIntArray(int size) {
			int[] array = new int[size];
			for (int i = 0; i < size; i++) {
				array[i] = nextInt();
			}
			return array;
		}
	}
 
}