#include<stdio.h>
FILE*fin,*fout;
unsigned long int n,i,j,s,tcurent,t1,t2,t3,u;
int main(){
 fin=fopen("koba.in","r");
 fout=fopen("koba.out","w");
 fscanf(fin,"%ld %ld %ld %ld",&n,&t1,&t2,&t3);
 s=0;
 fclose(fin);       s=(t1+t2+t3)%10;
 t1=t1%10; t2=t2%10; t3=t3%10;
 for(i=4;i<=n;i++) {
  tcurent=(t1*t2+t3)%10;
             s=s+tcurent;
  t1=t2;t2=t3;t3=tcurent;
 }

fprintf(fout,"%ld",s);
fclose(fout);

return 0;
}