#include<stdio.h>
FILE *f=fopen("koba.in","r"),
     *g=fopen("koba.out","w");
int i,j,t1,t2,t3,n,k,au,a[15][15][15];
int main()
{ fscanf(f,"%d %d %d %d",&n,&t1,&t2,&t3);
  for(i=0;i<=9;++i) for(j=0;j<=9;++j) { a[i][j][0]=i*j%10;
				      for(k=1;k<=9;++k) a[i][j][k]=(a[i][j][k-1]+1)%10;
				      }
  if(n==1) fprintf(g,"%d\n",t1%10);
  else if(n==2) fprintf(g,"%d\n",t1+t2%10);
  else if(n==3) fprintf(g,"%d\n",t1+t2+t3%10);
  else  { n-=3;k=t1%10+t2%10+t3%10;
	  t1%=10;t2%=10;t3%=10;
	  for(i=1;i<=n;++i) au=t1,t1=t2,t2=t3,t3=a[au][t1][t2],k+=t3;
	  fprintf(g,"%d\n",k);}
	  fclose(f);
	  fclose(g);
	  return 0;
}