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.
//package com.company;

import java.io.*;
import java.util.*;

import static java.lang.Math.*;

//public class LuckyTicketA {
        public class Main {

    public static void main(String[] args) throws IOException {
        Boolean arr[] = new Boolean[11];
        Arrays.fill(arr, false);
        arr[4] = true;
        arr[7] = true;
        int n= sc.nextInt();
        String str = sc.nextString();
        Boolean answer = true;
        for (int i = 0; i < str.length(); i++) {
            answer &= arr[str.charAt(i) - '0'];
        }
        int fstsum = 0;
        int lstsum = 0;
        if (answer) {
            for (int i = 0; i < n / 2; i++) {
                fstsum += str.charAt(i) - '0';
            }
            for (int i = n/2; i < n; i++) {
                lstsum += str.charAt(i) - '0';
            }
            answer=lstsum==fstsum;
        }
        out.println(answer ? "YES" : "NO");
        close.close();
    }






















    /* This is O(scary), but seems quick enough in practice. */

    static void debug(Object... obj) {
        System.err.println(Arrays.deepToString(obj).replace("], ", "]\n"));
    }

    static void debugV2(Object... obj) {
        System.out.println(Arrays.deepToString(obj)
                .replace("],", "\n").replace(",", "\t")
                .replaceAll("[\\[\\]]", " "));
    }

    static class Sc {
        final private int BUFFER_SIZE = 1 << 16;
        private DataInputStream din;
        private byte[] buffer;
        private int bufferPointer, bytesRead;

        public Sc() {
            din = new DataInputStream(System.in);
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public Sc(String file_name) throws IOException {
            din = new DataInputStream(new FileInputStream(file_name));
            buffer = new byte[BUFFER_SIZE];
            bufferPointer = bytesRead = 0;
        }

        public String readLine() throws IOException {
            byte[] buf = new byte[64]; // line length
            int cnt = 0, c;
            while ((c = read()) != -1) {
                if (c == '\n')
                    break;
                buf[cnt++] = (byte) c;
            }
            return new String(buf, 0, cnt);
        }

        public String nextString() throws IOException {
            StringBuilder sb = new StringBuilder();
            int n = read();
            while (isWhiteSpace(n))
                n = read();
            while (!isWhiteSpace(n)) {
                sb.append((char) n);
                n = read();
            }
            return sb.toString();
        }

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

        public int nextInt() throws IOException {
            int ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            } while ((c = read()) >= '0' && c <= '9');

            if (neg)
                return -ret;
            return ret;
        }

        public long nextLong() throws IOException {
            long ret = 0;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();
            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');
            if (neg)
                return -ret;
            return ret;
        }

        public double nextDouble() throws IOException {
            double ret = 0, div = 1;
            byte c = read();
            while (c <= ' ')
                c = read();
            boolean neg = (c == '-');
            if (neg)
                c = read();

            do {
                ret = ret * 10 + c - '0';
            }
            while ((c = read()) >= '0' && c <= '9');

            if (c == '.') {
                while ((c = read()) >= '0' && c <= '9') {
                    ret += (c - '0') / (div *= 10);
                }
            }

            if (neg)
                return -ret;
            return ret;
        }

        private void fillBuffer() throws IOException {
            bytesRead = din.read(buffer, bufferPointer = 0, BUFFER_SIZE);
            if (bytesRead == -1)
                buffer[0] = -1;
        }

        private byte read() throws IOException {
            if (bufferPointer == bytesRead)
                fillBuffer();
            return buffer[bufferPointer++];
        }

        public void close() throws IOException {
            if (din == null)
                return;
            din.close();
        }
    }


    static class Print {
        private final OutputStream out;

        public Print() {
            this.out = System.out;
        }

        public void print(String str) throws IOException {
            for (int i = 0; i < str.length(); i++) {
                out.write(str.charAt(i));
            }
        }

        public void println(String str) throws IOException {
            print(str);
            out.write('\n');
        }

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

    static Sc sc = new Sc();
    static Print out = new Print();
    static BufferedWriter close = new BufferedWriter(new OutputStreamWriter(System.out));
    // 11:54 PM Tue 02 2021 2/23/2021
}