/*
Se da un numar intreg P. Sa se gaseasca cel mai mic numar 
natural strict pozitiv N pentru care N! are exact P cifre 
de 0 la sfarsit.
*/

#include <stdio.h>

int main()
{
	FILE 	*in  = fopen("fact.in",  "rt"),
			*out = fopen("fact.out", "wt");

	long int P, i, q;
	fscanf(in, "%ld", &P);

	i = 0;
	q = 0;

	while(q < P)
	{
		i = i + 5;

		int aux = i;
		while(aux % 5 == 0)
		{
			q++;
			aux /= 5;
		}
	}

	if(q != P)
		fprintf(out, "-1");
	else
		fprintf(out, "%ld", i);

	fclose(in);
	fclose(out);
}