CodeForces 110A Nearly Lucky Number

Description

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.

Unfortunately, not all numbers are lucky. Petya calls a number nearly lucky if the number of lucky digits in it is a lucky number. He wonders whether number n is
a nearly lucky number.

Input

The only line contains an integer n (1 ≤ n ≤ 1018).

Please do not use the %lld specificator to read or write 64-bit numbers in С++. It is preferred to use the cin, cout streams or the %I64d specificator.

Output

Print on the single line "YES" if n is a nearly lucky number. Otherwise, print "NO"
(without the quotes).

Sample Input

Input

40047

Output

NO

Input

7747774

Output

YES

Input

1000000000000000000

Output

NO

Hint

In the first sample there are 3 lucky digits (first one and last two), so the answer is "NO".

In the second sample there are 7 lucky digits, 7 is lucky number, so the answer is "YES".

In the third sample there are no lucky digits, so the answer is "NO".

只需要判断字符串中‘4’和‘7’的总数是4个或者7个就行。

代码如下：

#include<stdio.h>
#include<string.h>
int main()
{
char a[20];
int i,n=0;
scanf("%s",a);
int len=strlen(a);
for(i=0;i<len;i++)
{
if(a[i]=='4'||a[i]=='7') n++;
}
if(n==4||n==7) printf("YES\n");
else printf("NO\n");
return 0;
}