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

long long int P,p,nr,ind;

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

    scanf("%llu\n", &P);
    while (p < P)
    {
       	nr += 5;
       	ind = nr;
     	while (ind % 5 == 0)
       	{
           	ind = ind / 5;
           	p++;
       	}
    }
    if (P==0) nr=1;    

    printf("%lli\n", nr);

}