Codeforces 146A Lucky Ticket

Lucky TicketTime limit:2000MS Memory Limit:262144KB 64bit IO Format:%i64d &%i6 4u SubmitStatusPracticecodeforces 146A

Description

petya loves lucky numbers very much. Everybody knows that lucky numbers is positive integers whose decimal record contains only the lucky Digits 4 and 7. For example, Numbers 47, 744, < Span class= "TEX-FONT-STYLE-BF" >4 are lucky and 5, 17, 467 are not.

Petya loves tickets very much. As we know, each ticket have a number that is a positive integer. Its length equals n (n are 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 th E First n /2 digits) equals the sum of digits in the second half (the sum of the last n /2 dig ITS). Check if the given ticket is lucky.

Input

The first line contains a even integer n(2≤ n ≤50)-the length of the ticket number that nee DS to is 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).

Sample Input

Input

2
47

Output

NO

Input

4
4738

Output

NO

Input

4
4774

Output

YES

Hint

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.

1#include <stdio.h>2#include <string.h>3#include <algorithm>4 using namespacestd;5 intMain ()6 {7     Chara[ the];8     intI,j,n;9      while(SCANF ("%d", &n)! =EOF)Ten     { One         intflg=1, s1=0, s2=0; Ascanf"%s", a); -          for(i=0; i<n;i++) -         { the             if(i<n/2) -s1=s1+a[i]-'0'; -             Else -s2=s2+a[i]-'0'; +             if(a[i]=='4'|| a[i]=='7') -             { +flg=1; A             } at             Else -             { -flg=0; -                  Break; -             } -         } in         //printf ("%d%d\n", s1,s2); -         if(s1!=S2) toflg=0; +         if(FLG) -printf"yes\n"); the         Else *printf"no\n"); $     }Panax Notoginseng     return 0; -}

View Code

Codeforces 146A Lucky Ticket