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