#include <cstdio> 
using namespace std;
int n, i, x, p, nr;
int main(){
	freopen("fact.in", "r", stdin);
	freopen("fact.out", "w", stdout);
	scanf("%d ", &p);
	if(p == 0)
		printf("1\n");
	else{
		i = 5;
		while(nr < p - 1){
			i += 5;
			int x = i;
			while(x > 0 && x % 5 == 0)
				++nr,
				x /= 5;
		}
		printf("%d\n", i);
	}
	return 0;
}