#include<stdio.h>
#include<math.h>

int main(){
FILE *fin=fopen("cifra.in","r");
FILE *fout=fopen("cifra.out","w");
unsigned long N,i,u,sum;

fscanf(fin,"%ld",&N);
sum=0;
 for(i=1;i<N+1;i++){
  if(i%10==2 || i%10==8)
   if(i%4==0) sum+=6;
    else sum+=4;
  else if(i%10==3 || i%10==7)
   if(i%4==1) sum+=i%10;
    else sum+=(i%10)>3?3:7;
  else if(i%10==4) sum+=6;
  else sum+=i%10;
 }
/* asum=floorl(sum/10);
 asum*=10;
 asum=sum-asum;*/
fprintf(fout,"%d",sum%10);
fclose(fin);
fclose(fout);
return 0;
}