#include<stdio.h>

int main()
{
	freopen("fact.in","r",stdin);
	freopen("fact.out","w",stdout);

	long long unsigned p,i,c5=0,aux;
	scanf("%llu",&p);
	while(c5!=p)
		for(i=2;i;++i)
		{
			aux=i;
			while(aux)
				if(aux%5==0)
				{
					++c5;
					aux/=5;
					if(c5==p)
					{
						printf("%llu",i);
						return 0;
					}
				}
				else
					break;
		}

	return 0;
}