#include <cstdio>

int n;
int zero(int x)
{
	int rez=0;
	while(x)
	{
		rez+=x/5;
		x/=5;
	}
	return rez;
}

int caut(int p)
{
	int i,pas=1<<30;
	for(i=0;pas;pas>>=1)
		if(zero(i+pas)<p)
			i+=pas;
	return i+1;
}
void afis()
{
	if(zero(caut(n))==n)
		printf("%d",caut(n));
	else
		printf("-1");
}
int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);
	scanf("%d",&n);
	afis();
	return 0;
}