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