#include <stdio.h>
#include <math.h>
long n,p;
int main ()
{
    freopen ("fact.in","r",stdin);
    freopen ("fact.out","w",stdout);
    float i;
    int j;
    scanf ("%ld",&p);
    if (p==0)
    {
       printf ("1");return 0;
    }
    n=p*5;
    i=sqrt(n);
    j=(int)i;
    n-=j-1;
    printf ("%ld",n);
    return 0;
}