A. Nearly Lucky Number

time limit per test

2 seconds

memory limit per test

256 megabytes

input

standard input

output

standard output

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 ≤ 10^18).

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 test(s)input

40047

output

NO

input

7747774

output

YES

input

1000000000000000000

output

NO

Note

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".

解題說明：此題不要被題目輸入資訊誤導了，不是要把輸入的數當成一個很大的數，而是應該看成一個字串，然後從中找出4和7的個數統計即可，最後在用模10來計算個數是否為幸運數

#include <iostream>#include<cstdio>#include<cstring>#include<cmath>using namespace std;int main(){char a[20];int i,sum;int flag;sum=0;flag=0;scanf("%s",&a);for(i=0;a[i]!='\0';i++){if(a[i]=='4'||a[i]=='7'){sum++;}}if(sum==0){flag=1;}else{while(1){if(sum%10!=4&&sum%10!=7){flag=1;break;}sum=sum/10;if(sum==0){break;}}}if(flag==0){printf("YES\n");}else{printf("NO\n");}return 0;}