#include<stdio.h>


typedef unsigned long long int big;

big fact(big a)
{
	big i,rez=1;
	if (a==0) return 1;
	for (i=1;i<=a;i++)
	{
		rez=rez*i;
	}
	return rez;
}
int cif(big a)
{
    big c,s=0;
	while(a!=0)
	{
		
		c=(a % 10);
		a=a / 10;
		if (c==0) s++; else if (c!=0) 
		{ 
			
			return s;
		}
	}
}
int main()
{
	FILE *in=fopen("fact.in","r"),
		 *out=fopen("fact.out","w");

	big a,b,c;
	fscanf(in,"%llu",&a);
	
	for (b=1;b<=9999999;b++)
	{
		c=fact(b);
	   
		if (cif(c)==a)
		{
			fprintf(out,"%llu",b);
			goto sf;
		}
	}
	
	
	
sf:
     return 0;

}