#include<stdio.h>
#define MAX_LIST 10000

int lista[MAX_LIST];

int main()
{
	FILE* f = fopen("fact.in", "r");
	int p;
	fscanf(f, "%d", &p);
	if(p == 0)
		return 1;
	int i = 0;
	int N = 0;
	while(i != p)
	{
		N+=5;
		int aux = N;
		while( aux % 5 == 0 )
		{
			aux /= 5;
			i++;
		}
	}
	fclose(f);
	f = fopen("fact.out", "w");
	fprintf(f, "%d", N);
	fclose(f);
	return 0;
}