#include <stdio.h>
 #include <math.h>
int main()
 {
     FILE *f=fopen("cifra.in","r"),*g=fopen("cifra.out", "w");
 int a,c,d;
 int b=1;
 int e=0;
 scanf (f,"%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 (g,"%d \n",c);
return 0;
}