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.
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.
Print on the single line "YES" if n is a nearly lucky number. Otherwise, print "NO" (without the quotes).
40047
NO
7747774
YES
1000000000000000000
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".
#include<stdio.h> int lucky(long long a) { if (a == 4 || a == 7) return 0; if (a == 0) return -1; else { while (a != 0) { if (a % 10 == 4 || a % 10 == 7) a = a / 10; else return -1; } return 0; } } void main() { long long m; scanf("%lld", &m); long long sum = 0; while (m != 0) { if (m % 10 == 4 || m % 10 == 7) sum++; m = m / 10; } if (lucky(sum) == 0) printf("YES "); else printf("NO "); }