#include<stdio.h>   

int main(){ 
	int i,n,c=0;
	scanf("%d",&n);

	
	for(i = 5;i <= n;i++){
		int w = i / 10000;
		int q = i / 1000 % 10;
		int b = i / 100 % 10;
		int s = i / 10 % 10;
		int g = i % 10;
		
		if((w == 5 || q == 5 || b == 5 || s == 5 || g == 5) && i % 5 == 0){
		
			c++;
		}
	}
	
	printf("%d",c);
	return 0;
} 
/**************************************************************
	Problem: 1057
	User: admin
	Language: C
	Result: Accepted
	Time:18 ms
	Memory:1144 kb
****************************************************************/