#include <stdio.h>
#include <stdlib.h>

int main()
{
    int p,nr5;
    long long n,nc;
    freopen("factorial.in","r",stdin);
    freopen("factorial.out","w",stdout);
    scanf("%d",&p);
    n=0;
    nr5=0;
    do
    {
        n++;
        nc=n;
        while(nc%5==0)
            nr5++,nc/=5;
    }while(nr5<p);
    if(nr5>p)
        printf("-1\n");
    else
        printf("%lld\n",n);

    return 0;
}