#include <stdio.h>


int main()
{
    freopen("fact.in","r",stdin);
    freopen("fact.out","w",stdout);
    long long int p,n,ok,ok1,i,s;
    scanf("%lld",&p);
    ok=0;
    n=1;
    while(ok==0)
    {
        i=1;
        s=1;
        while(i<=n)
        {
            s=s*i;
            i++;
        }
        ok1=1;
        for(i=1;i<=p && s;i++)
        {
            if(s%10!=0)
            {
                ok1=0;
                break;
            }
            s=s/10;
        }
        if(ok1==1)
        {
            ok=1;
            printf("%lld",n);
        }
        n++;
    }






    return 0;
}