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.io.*;
import java.util.*;
import java.text.*;
import java.math.*;
import java.util.regex.*;
import java.lang.*;

public class P146A {
    //static long m=1000000007;
    static BigInteger ways(int N,  int K) {
        BigInteger ret = BigInteger.ONE;
        for(int i=N;i>=N-K+1;i--)
        {
             ret = ret.multiply(BigInteger.valueOf(i));
            
        }
        for (int j = 1; j<=K; j++) {
            ret = ret.divide(BigInteger.valueOf(j));
        }
       
            ret=ret.mod(BigInteger.valueOf(1000000007));
        
        return ret;
    }
    public static int prime(int n)
    {
        int f=1;
        if(n==1)
            return 0;
        for(int i=2;i<=(Math.sqrt(n));)
        {
            if(n%i==0)
            {
                f=0;
                break;
            }
            if(i==2)
                i++;
            else
                i+=2;
        }
        if(f==1)
            return 1;
        else 
            return 0;
    }
/*public static long gcd(long x,long y)
{
    if(x%y==0)
        return y;
    else return gcd(y,x%y);
}*/
    public static BigInteger fact(int n)
    {
        BigInteger f=BigInteger.ONE;
        for(int i=1;i<=n;i++)
        {
            f=f.multiply(BigInteger.valueOf(i));
        }
        //f=f.mod(BigInteger.valueOf(m));
        return f;
    }
public static int gcd(int x,int y)
{
    if(x%y==0)
        return y;
    else return gcd(y,x%y);
}
public static long max(long a,long b)
{if(a>b)
    return a;
else
    return b;
}
public static int max(int a,int b)
{
    if(a>b)
        return a;
    else
        return b;
}
public static long min(long a,long b)
{
    if(a>b)
        return b;
    else 
        return a;
}
public static int min(int a,int b)
{
    if(a>b)
        return b;
    else 
        return a;
}
static int knapsack(int wt[], int W, int n)
{
  int i, w;
  int K[][]=new int[n+1][W+1];

  // Build table K[][] in bottom up manner
  for (i = 0; i <= n; i++)
  {
      for (w = 0; w <= W; w++)
      {
          if (i==0 || w==0)
              K[i][w] = 0;
          else if (wt[i-1] <= w)
                K[i][w] = (int)Math.max(wt[i-1] + K[i][w-wt[i-1]],  K[i-1][w]);
          else
                K[i][w] = K[i-1][w];
      }
  }

  return K[n][W];
}
   static int knapsack1(int arr[],int sum,int n) 
   { 
       if(n<0)
           return 0; 
       if(sum-arr[n]<0) 
           return knapsack(arr,sum,n-1); 
       return (int)Math.max(knapsack(arr,sum-arr[n],n)+arr[n],knapsack(arr,sum,n-1)); 
   }

   static int NumberOfSetBits(int i)
   {
        i = i - ((i >> 1) & 0x55555555);
        i = (i & 0x33333333) + ((i >> 2) & 0x33333333);
        return (((i + (i >> 4)) & 0x0F0F0F0F) * 0x01010101) >> 24;
   }
    public static void main(String[] args) throws Exception{
        
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringBuilder sb=new StringBuilder("");
        //int t=Integer.parseInt(br.readLine());
    //  while(t-->0)
        //{
        //int n=Integer.parseInt(br.readLine());
        //long n=Long.parseLong(br.readLine());
        //String l[]=br.readLine().split(" ");
        //int m=Integer.parseInt(l[0]);
        //int k=Integer.parseInt(l[1]);
        //l=br.readLine().split(" ");
        //long m=Long.parseLong(l[0]);
        //long n=Long.parseLong(l[1]);
        //char ch=a.charAt();
    //  char c[]=new char[n];
        /*int a[]=new int[n];
        for(int i=0;i<n;i++)
        {
            a[i]=Integer.parseInt(l[i]);
        }*/
        /*long a[]=new long[n];
        for(int i=0;i<n;i++)
        {
            a[i]=Long.parseLong(l[i]);
        }*/
        /*int a[][]=new int[n][n];
        for(int i=0;i<n;i++)
        {
        l=br.readLine().split(" ");
            for(int j=0;j<n;j++)
            {
                a[i][j]=Long.parseLong(l[j]);
            }
        }*/
        
        //  String a=br.readLine();
        
        // char a[]=c.toCharArray();
        //char ch=l[0].charAt(0);
        
        //HashMap<Integer,Integer>hm=new HashMap<Integer,Integer>();
        //HashMap<Integer,String>hm=new HashMap<Integer,String>();
        //HashMap<Integer,Long>hm=new HashMap<Integer,Long>();
        //hm.put(1,1);
        //HashSet<Integer>hs=new HashSet<Integer>();
        //HashSet<Long>hs=new HashSet<Long>();
        //HashSet<String>hs=new HashSet<String>();
        //hs.add(x);
        //Stack<Integer>s=new Stack<Integer>();
        //s.push(x);
        //s.pop(x);
        //Queue<Integer>q=new LinkedList<Integer>();
        //q.add(x);
        //q.remove(x);
        //ArrayList<Integer>ar=new ArrayList<Integer>();
        //long x=Long.parseLong(l[0]);
        
        //int min=100000000;
    
        //long c1=(long)Math.ceil(n/(double)a);
        //Arrays.sort(a);
          // int f1[]=new int[26];
           //int f2[]=new int[26];
        /*for(int i=0;i<n;i++)
        {
        int x=a.charAt(0);
            f1[x-97]++;
        }*/
        /*for(int i=0;i<n;i++)
        {
            
        }*/
        /*for(int i=0;i<n;i++)
        {
            for(int j=0;j<n;j++)
            {
                
            }
        }*/
        /*while(q--)
          {
                l=br.readLine().split(" ");
                int n=Integer.parseInt(l[0]);
                int k=Integer.parseInt(l[1]);
          }
         */
        int n=Integer.parseInt(br.readLine());
        String a=br.readLine();
        char c[]=a.toCharArray();
        
        int f=1;
        if(n%2==1)
            f=0;
        int s1=0,s2=0;
        for(int i=0,j=n-1;i<n/2;i++,j--)
        {
            if(c[i]=='4'||c[i]=='7')
            {
                s1+=c[i];
            }
            else
            {
                f=0;
                break;
            }
            if(c[j]=='4'||c[j]=='7')
            {
                s2+=c[j];
            }
            else
            {
                f=0;
                break;
            }
        }
        if(s1!=s2)
            f=0;
        if(f==1)
            System.out.println("YES");
        else
            System.out.println("NO");
        
            
                
        

    }
}