#include<fstream.h>
#include<math.h>

ifstream citeste("fact.in");
ofstream scrie("fact.out");

unsigned long int fact (int n)
	{
	int f=1;
	for (int i=1;i<=n;i++)
		f*=i;
	return f;
	}

int main()
	{
	unsigned long int p,n=1,b=0,x,y;
	citeste>>p;
	y=pow(10,p);
	while (b==0)
		{
		x=fact(n);
                if (x%y==0) {scrie<<n;b=1;}
		n++;
		}
	citeste.close();
	scrie.close();
	return 0;
	}