#include <stdio.h>

long long fact(long long a){
	if (a == 0)
		return 1;
	else
		if(a == 1)
			return 1;
		else
			return a * fact(a-1);
}

long long nrcif(long long a){
long long ct;
	ct = 0;
	while(a != 0){
		a = a / 10;
		ct++;

	}

	return ct;


}

int main () {
long long p;
long long ct,i;
	freopen("fact.in","r",stdin);
	scanf("%lld",&p);
	fclose(stdin);
	
	ct = 0;
	i = 0;
	while(ct <= p){
		if(i % 5 == 0)
			ct++;
		i++;	


	}

	freopen("fact.out","w",stdout);
	if(p == 0)
		printf("%d",1);
	else
		printf("%lld",i);
		
	fclose(stdout);

	return 0;
}