#include <iostream>
#include <bits/stdc++.h>
using namespace std;

int main() {
	string s ;
	cin>>s;
	int k ; cin>>k;
	int n = s.size();
	int ans = 0 ; 
	for(int i = 0 ; i<n;i++){
		int count = 0 ; 
		for(int j = i;j<n;j++){
			if(s[j]=='5')count++;
			if(count==k) ans++;
		}
	}
	
	cout<<ans;
	// your code goes here
	return 0;
}