#include<bits/stdc++.h>
using namespace std;
int main(){
	int i=1,n,a,b,c,d,e,h;
	cin>>n;
	for(i=1;i<=n;i++){
		a=i%10;
		b=i/10%10;
		c=i/100%10; 
		d=i/1000%10;
		e=i/10000;
		if(i%5==0||a==5||b==5||c==5||d==5||e==5)
		h++;
	}
        cout<<h<<enl;
}

/**************************************************************
	Problem: 1057
	User: wengsihan
	Language: C++
	Result: Compile Error
****************************************************************/