#include <stdio.h>
#include <math.h>

long n,m;

int fact(long p)
{int i;
if (p==0) return 1;
	else
	{
		m=1;
		for(i=1;m<=p;i++)
			m+=pow(5,i);
		m-=pow(5,--i);
		n=5*ceil(p*pow(5,i-1)/m);
	}
return n;
}

int main(char *argv[],int argc)
{
	long p;
	int i;
	FILE *f;
	f=fopen("fact.in","rt");
	fscanf(f,"%d",&p);
	fclose(f);
	f=fopen("fact.out","wt");
	i=fact(p);
	if (i==fact(p+1)) fprintf(f,"%d",-1);
	else fprintf(f,"%d",i);
	return 0;
}