#include <stdio.h>
 #include <math.h>
int main(){  
          int a,c,d;
          int b=1;
          int e=0;
          int i=0;
freopen("cifra.in", "r", stdin);
freopen("cifra.out", "w", stdout);
 scanf ("%d",&a);  
 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);
return 0;
}