#include <stdio.h>
 #include <math.h>
int main()
 {
        freopen ("adunare.in","r",stdin);
    freopen ("adunare.out","w",stdout);        
 int a,c,d;
 int b=1;
 int e=0;
 scanf ("%d",&a);  
 int i=0;
 while (i<a)
{
               d=pow(b,b);
               c=d+e;
               e=c;
               b=b+1;
               i=i+1;
}
c=c%10;
printf ("%d \n",c);
}