Petya loves lucky numbers very much. Everybody knows that lucky numbers are positive integers whose decimal record contains only the lucky digits 4 and 7. For example, numbers 47, 744, 4 are lucky and 5, 17, 467 are not.

Petya loves tickets very much. As we know, each ticket has a number that is a positive integer. Its length equals n (n is always even). Petya calls a ticket lucky if the ticket's number is a lucky number and the sum of digits in the first half (the sum of the first n / 2 digits) equals the sum of digits in the second half (the sum of the last n / 2 digits). Check if the given ticket is lucky.

Input

The first line contains an even integer n (2 ≤ n ≤ 50) — the length of the ticket number that needs to be checked. The second line contains an integer whose length equals exactly n — the ticket number. The number may contain leading zeros.

Output

On the first line print "YES" if the given ticket number is lucky. Otherwise, print "NO" (without the quotes).

Examples

Input

2
47


Output

NO


Input

4
4738


Output

NO


Input

4
4774


Output

YES

Note

In the first sample the sum of digits in the first half does not equal the sum of digits in the second half (4 ≠ 7).

In the second sample the ticket number is not the lucky number.
import java.awt.*;
import java.io.*;
import java.math.*;
import java.nio.charset.MalformedInputException;
import java.util.*;
import static java.lang.Math.*;

public class CF104_Div2_A implements Runnable {

	BufferedReader in;
	PrintWriter out;
	StringTokenizer tok = new StringTokenizer("");

	public static void main(String[] args) {
		new Thread(null, new CF104_Div2_A(), "", 256 * (1L << 20)).start();
	}

	public void run() {
		try {
			long t1 = System.currentTimeMillis();
			if (System.getProperty("ONLINE_JUDGE") != null) {
				in = new BufferedReader(new InputStreamReader(System.in));
				out = new PrintWriter(System.out);
			} else {
				in = new BufferedReader(new FileReader("input.txt"));
				out = new PrintWriter("output.txt");
			}
			Locale.setDefault(Locale.US);
			solve();
			in.close();
			out.close();
			long t2 = System.currentTimeMillis();
			System.err.println("Time = " + (t2 - t1));
		} catch (Throwable t) {
			t.printStackTrace(System.err);
			System.exit(-1);
		}
	}

	String readString() throws IOException {
		while (!tok.hasMoreTokens()) {
			tok = new StringTokenizer(in.readLine());
		}
		return tok.nextToken();
	}

	int readInt() throws IOException {
		return Integer.parseInt(readString());
	}

	long readLong() throws IOException {
		return Long.parseLong(readString());
	}

	double readDouble() throws IOException {
		return Double.parseDouble(readString());
	}
	
	BigInteger readBigInteger() throws IOException {
		return new BigInteger(readString());
	}
	
	void debug(Object... objects) {
		System.err.println(Arrays.deepToString(objects));
	}

	static class Utils {

		private Utils() {}
		
		
		private static final int MAGIC_VALUE = 50;
		

		public static void mergeSort(int[] a) {
			mergeSort(a, 0, a.length - 1);
		}
		public static void mergeSort(long[] a) {
			mergeSort(a, 0, a.length - 1);
		}
		public static void mergeSort(double[] a) {
			mergeSort(a, 0, a.length - 1);
		}


		private static void mergeSort(int[] a, int leftIndex, int rightIndex) {
			if (leftIndex < rightIndex) {
				if (rightIndex - leftIndex <= MAGIC_VALUE) {
					insertionSort(a, leftIndex, rightIndex);
				} else {
					int middleIndex = (leftIndex + rightIndex) / 2;
					mergeSort(a, leftIndex, middleIndex);
					mergeSort(a, middleIndex + 1, rightIndex);
					merge(a, leftIndex, middleIndex, rightIndex);
				}
			}
		}
		private static void mergeSort(long[] a, int leftIndex, int rightIndex) {
			if (leftIndex < rightIndex) {
				if (rightIndex - leftIndex <= MAGIC_VALUE) {
					insertionSort(a, leftIndex, rightIndex);
				} else {
					int middleIndex = (leftIndex + rightIndex) / 2;
					mergeSort(a, leftIndex, middleIndex);
					mergeSort(a, middleIndex + 1, rightIndex);
					merge(a, leftIndex, middleIndex, rightIndex);
				}
			}
		}
		private static void mergeSort(double[] a, int leftIndex, int rightIndex) {
			if (leftIndex < rightIndex) {
				if (rightIndex - leftIndex <= MAGIC_VALUE) {
					insertionSort(a, leftIndex, rightIndex);
				} else {
					int middleIndex = (leftIndex + rightIndex) / 2;
					mergeSort(a, leftIndex, middleIndex);
					mergeSort(a, middleIndex + 1, rightIndex);
					merge(a, leftIndex, middleIndex, rightIndex);
				}
			}
		}

		
		private static void merge(int[] a, int leftIndex, int middleIndex, int rightIndex) {
			int length1 = middleIndex - leftIndex + 1;
			int length2 = rightIndex - middleIndex;
			int[] leftArray = new int[length1];
			int[] rightArray = new int[length2];
			System.arraycopy(a, leftIndex, leftArray, 0, length1);
			System.arraycopy(a, middleIndex + 1, rightArray, 0, length2);
			for (int k = leftIndex, i = 0, j = 0; k <= rightIndex; k++) {
				if (i == length1) {
					a[k] = rightArray[j++];
				} else if (j == length2) {
					a[k] = leftArray[i++];
				} else {
					a[k] = leftArray[i] <= rightArray[j] ? leftArray[i++] : rightArray[j++];
				}
			}
		}
		private static void merge(long[] a, int leftIndex, int middleIndex, int rightIndex) {
			int length1 = middleIndex - leftIndex + 1;
			int length2 = rightIndex - middleIndex;
			long[] leftArray = new long[length1];
			long[] rightArray = new long[length2];
			System.arraycopy(a, leftIndex, leftArray, 0, length1);
			System.arraycopy(a, middleIndex + 1, rightArray, 0, length2);
			for (int k = leftIndex, i = 0, j = 0; k <= rightIndex; k++) {
				if (i == length1) {
					a[k] = rightArray[j++];
				} else if (j == length2) {
					a[k] = leftArray[i++];
				} else {
					a[k] = leftArray[i] <= rightArray[j] ? leftArray[i++] : rightArray[j++];
				}
			}
		}
		private static void merge(double[] a, int leftIndex, int middleIndex, int rightIndex) {
			int length1 = middleIndex - leftIndex + 1;
			int length2 = rightIndex - middleIndex;
			double[] leftArray = new double[length1];
			double[] rightArray = new double[length2];
			System.arraycopy(a, leftIndex, leftArray, 0, length1);
			System.arraycopy(a, middleIndex + 1, rightArray, 0, length2);
			for (int k = leftIndex, i = 0, j = 0; k <= rightIndex; k++) {
				if (i == length1) {
					a[k] = rightArray[j++];
				} else if (j == length2) {
					a[k] = leftArray[i++];
				} else {
					a[k] = leftArray[i] <= rightArray[j] ? leftArray[i++] : rightArray[j++];
				}
			}
		}

		
		private static void insertionSort(int[] a, int leftIndex, int rightIndex) {
			for (int i = leftIndex + 1; i <= rightIndex; i++) {
				int current = a[i];
				int j = i - 1;
				while (j >= leftIndex && a[j] > current) {
					a[j + 1] = a[j];
					j--;
				}
				a[j + 1] = current;
			}
		}
		private static void insertionSort(long[] a, int leftIndex, int rightIndex) {
			for (int i = leftIndex + 1; i <= rightIndex; i++) {
				long current = a[i];
				int j = i - 1;
				while (j >= leftIndex && a[j] > current) {
					a[j + 1] = a[j];
					j--;
				}
				a[j + 1] = current;
			}
		}
		private static void insertionSort(double[] a, int leftIndex, int rightIndex) {
			for (int i = leftIndex + 1; i <= rightIndex; i++) {
				double current = a[i];
				int j = i - 1;
				while (j >= leftIndex && a[j] > current) {
					a[j + 1] = a[j];
					j--;
				}
				a[j + 1] = current;
			}
		}

	}
	
	boolean isLucky(long x) {
		if (x == 0) return false;
		while (x > 0) {
			if (x % 10 != 4 && x % 10 != 7) return false;
			x /= 10;
		}
		return true;
	}
	
	long[] generateLuckyNumbers(long limit) {
		ArrayList<Long> list = new ArrayList<Long>();
		int maxLen = Long.toString(limit).length();
		for (int len = 1; len <= maxLen; len++) {
			for (int mask = 0; mask < (1 << len); mask++) {
				long num = 0;
				for (int i = 0; i < len; i++) {
					if (((1 << i) & mask) == 0) {
						num = num * 10 + 4;
					} else {
						num = num * 10 + 7;
					}
				}
				if (num <= limit) {
					list.add(num);
				}
			}
		}
		long[] res = new long[list.size()];
		for (int i = 0; i < res.length; i++) {
			res[i] = list.get(i);
		}
		Utils.mergeSort(res);
		return res;
	}

	// solution

	void solve() throws IOException {
		int n = readInt();
		char[] s = readString().toCharArray();
		for (int i = 0; i < n; i++) {
			if (s[i] != '4' && s[i] != '7') {
				out.println("NO");
				return;
			}
		}
		int sum1 = 0, sum2 = 0;
		for (int i = 0, j = n-1; i < n/2; i++, j--) {
			sum1 += s[i] - '0';
			sum2 += s[j] - '0';
		}
		out.println((sum1 == sum2) ? "YES" : "NO");
	}

}
