#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <algorithm>
using namespace std;

int p;

int is(int n) {
	int k = 0;
	int s = 5;
	while(s <= n) {
		for(int i = 1; i <= n; i++)
			if(i % s == 0) k++;
		s *= 5;
	}
	return k;
}

void solve() {
	freopen("fact.in", "r", stdin);
	freopen("fact.out", "w", stdout);
	scanf("%d", &p);
	for(int i = 1; ; ++i)
		if(is(i) == p) {
			printf("%d", i);
			return;
		}
}

int main() {
	solve();
}