Problem: Petya loves lucky numbers. We all know that lucky numbers are the positive integers whose decimal representations contain only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya and his friend Vasya play an interesting game. Petya randomly chooses an integer p from the interval [pl, pr] and Vasya chooses an integer v from the interval [vl, vr] (also randomly). Both players choose their integers equiprobably. Find the probability that the interval [min(v, p), max(v, p)] contains exactly k lucky numbers.

Input

The single line contains five integers pl, pr, vl, vr and k (1 ≤ pl ≤ pr ≤ 109, 1 ≤ vl ≤ vr ≤ 109, 1 ≤ k ≤ 1000).

Output

On the single line print the result with an absolute error of no more than 10 - 9.

Examples

Input

1 10 1 10 2


Output

0.320000000000


Input

5 6 8 10 1


Output

1.000000000000

Note

Consider that [a, b] denotes an interval of integers; this interval includes the boundaries. That is, <image>

In first case there are 32 suitable pairs: (1, 7), (1, 8), (1, 9), (1, 10), (2, 7), (2, 8), (2, 9), (2, 10), (3, 7), (3, 8), (3, 9), (3, 10), (4, 7), (4, 8), (4, 9), (4, 10), (7, 1), (7, 2), (7, 3), (7, 4), (8, 1), (8, 2), (8, 3), (8, 4), (9, 1), (9, 2), (9, 3), (9, 4), (10, 1), (10, 2), (10, 3), (10, 4). Total number of possible pairs is 10·10 = 100, so answer is 32 / 100.

In second case Petya always get number less than Vasya and the only lucky 7 is between this numbers, so there will be always 1 lucky number.

Solution (in JAVA):

Solution:
import java.io.BufferedReader;
import java.io.BufferedWriter;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.OutputStreamWriter;
import java.io.PrintWriter;
import java.util.Arrays;
import java.util.StringTokenizer;

public class LuckyProbability {
	BufferedReader in;
	PrintWriter out;
	StringTokenizer tokenizer;
	final double EPSILON = 1e-6;
	final int INF = (1 << 31) - 1;
	int pl, pr, vl, vr, k;
	int[] luckyNumbers;
	int cnt, a, b;

	LuckyProbability() {
		in = new BufferedReader(new InputStreamReader(System.in));
		out = new PrintWriter(new BufferedWriter(new OutputStreamWriter(
				System.out)));
		luckyNumbers = new int[1 << 20];
	}

	public void close() throws IOException {
		out.close();
		in.close();
	}

	public void enter() throws IOException {
		pl = nextInt();
		pr = nextInt();
		vl = nextInt();
		vr = nextInt();
		k = nextInt();
		solve();

	}

	void iteratate(long n) {
		if (n <= b) {
			if (n >= a)
				luckyNumbers[cnt++] = (int) n;
			iteratate(n * 10 + 4);
			iteratate(n * 10 + 7);
		}
	}

	public void solve() {

		cnt = 0;
		a = Math.min(pl, vl);
		b = Math.max(pr, vr);
		int minLeft, minRight, maxLeft, maxRight;
		iteratate(0);
		Arrays.sort(luckyNumbers, 0, cnt);
		// for (int i = 0; i < cnt; i++)
		// out.println(luckyNumbers[i]);
		long numStates = 1L * (pr - pl + 1) * (vr - vl + 1);
		long luckyStates = 0;
		for (int i = 0; i + k - 1 < cnt; i++) {
			if (i > 0)
				minLeft = luckyNumbers[i - 1] + 1;
			else
				minLeft = a;
			maxLeft = luckyNumbers[i];
			minRight = luckyNumbers[i + k - 1];
			if (i + k - 1 < cnt - 1)
				maxRight = luckyNumbers[i + k] - 1;
			else
				maxRight = b;
			luckyStates += 1L * count(pl, pr, minLeft, maxLeft)
					* count(vl, vr, minRight, maxRight);
			luckyStates += 1L * count(vl, vr, minLeft, maxLeft)
					* count(pl, pr, minRight, maxRight);
		}
		// should care corner case :(
		if (k == 1) {
			for (int i = 0; i < cnt; i++)
				if (luckyNumbers[i] >= pl && luckyNumbers[i] >= vl
						&& luckyNumbers[i] <= pr && luckyNumbers[i] <= vr)
					luckyStates--;
		}

		// out.println(luckyStates);
		// out.println(numStates);
		out.println(1.0 * luckyStates / numStates);

	}

	int count(int start, int end, int min, int max) {
		if (min > end || max < start)
			return 0;
		int _start, _end;
		_start = Math.max(start, min);
		_end = Math.min(end, max);
		if (end < start)
			return 0;
		return _end - _start + 1;
	}

	public static void main(String[] args) throws IOException {
		LuckyProbability obj = new LuckyProbability();
		obj.enter();
		obj.close();
	}

	int nextInt() throws IOException {
		return Integer.parseInt(nextToken());
	}

	long nextLong() throws IOException {
		return Long.parseLong(nextToken());
	}

	double nextDouble() throws IOException {
		return Double.parseDouble(nextToken());
	}

	String nextToken() throws IOException {
		while (tokenizer == null || !tokenizer.hasMoreTokens()) {
			tokenizer = new StringTokenizer(in.readLine());
		}
		return tokenizer.nextToken();
	}
}