#include <iostream>
#include <fstream>

using namespace std;

long factorial(int n) {
	if (n == 0 || n ==1)
		return 1;
	else return n * factorial(n-1);
}

long smallestNo(int p) {
	long output = 0;
	long multipliesFound = 0;

	while (multipliesFound < p) {
		output += 5;

		long temp = output;
		long multiplies = 0;
		while (temp%5 == 0) {
			multiplies++;
			temp = temp/5;
		}
		multipliesFound += multiplies;
	}

	if (output == 0) output = 1;
	return output;
}

int main(void) {
	ifstream f("fact.in");
	ofstream g("fact.out");
	long p;
	f>>p;
	long output = smallestNo(p);
	g<<output;
	return 0;
}