#include<stdio.h>
int main(){
	int p,n,i=1;
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&p);
	for(i=5;p;i+=5){
		n=i;
		if(n%125==0)
			while(n%125==0){
				p-=3;
				n/=125;
			}
		if(n%25==0)
			p-=2;
		else
			if(n%5==0)
				p--;
	}
	i-=5;
	if(i==0)
		i++;
	printf("%d\n",i);
	fclose(stdin);
	fclose(stdout);
	return 0;
}