#include<iostream>
#include<fstream>
#include<stdlib.h>
#include <climits>

using namespace std;

int n;
ifstream fin("fact.in");
ofstream fout("fact.out");

void citire(){
	fin>>n;
}

int rezolvare(int k){
	int aux,c=0;
	for(int i=5;;i+=5){
		aux =i;
		if(k<0)
			return -1;
		while(aux%5==0)
		{
			aux/=5;
			c++;
		}
		if(c!=0)
			k-=c;
		if(k == 0)
			return i;
	}
}

int main(){
	
	citire();
	if(n==0) 
		fout<<1;
	else
		fout<<rezolvare(n);
	return 0;
}