A8194 | Nearly Lucky Number
时间限制1s
内存限制256MB
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题目描述
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.
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.
输入格式
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.
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.
输出格式
Print on the single line "YES" if $n$ is a nearly lucky number. Otherwise, print "NO" (without the quotes).
输入输出样例
输入 #1
40047
输出 #1
NO
输入 #2
7747774
输出 #2
YES
输入 #3
1000000000000000000
输出 #3
NO
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".
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".
C++ 编辑器
输入
输出
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你好，我是作答助手。可以问思路、复杂度、样例含义或代码报错原因；不会直接给出完整 AC 代码。
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评测结果：Accepted