#include<stdio.h>

int main()

{

freopen ("factorial.in","r",stdin);
freopen ("factorial.out","w",stdout);

int p;

scanf ("%d",&p);

int nr2=0,nr5=0,i,nr0=0,cnr5=0;

if (p==0)
    printf ("1");

while (nr2<=p)
    {
        //nr2++;
        nr5++;
        cnr5++;
        nr0+=nr5;
        //nr2=0;
        nr5=0;
        if (nr0>=p)
            break;
        //nr2++;
        nr5++;
        cnr5++;
        nr0+=nr5;
        //nr2=0;
        nr5=0;
        if (nr0>=p)
            break;
    }

printf ("%d",(nr0-1)*cnr5/2);

return 0;
}