#include <stdio.h>
#include <stdlib.h>
#include <math.h>
int main(int argc, char *argv[])
{    
     int k,j,val,c,suma=0;
     FILE *i;
     FILE *o;
     i=fopen("cifra.in","r");
     o=fopen("cifra.out","w");
     fscanf(i,"%d",&j);
    
    for(k=1;k<=j;k++)
    {
     val=pow(k,k);
     suma+=val;
     }
     c=suma%10;
     fprintf(o,"%d",c);
     fclose(i);
     fclose(o);
  return 0;
}