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