#include<stdio.h>
long p,n,x,f5;
int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    scanf("%d",&p);
    n=4;
    do
    {
        n++;
        x=n;
        while(x%5==0)
        {
                     f5++;
                     x/=5;
        }
    }
    while(f5<p);
    printf("%ld",n);
    return 0;
}