#include<stdio.h>
int n,i,s=0,t1,t2,t3;
char t[10000000];
int main ()
{

FILE *f=fopen("koba.in","r");
FILE *g=fopen("koba.out","w");

fscanf(f,"%d %d %d %d",&n,&t1,&t2,&t3);
t[1]=t1%10;t[2]=t2%10;t[3]=t3%10;
s=s+t[1]+t[2]+t[3];
for (i=4;i<=n;i++)
    {t[i]=(t[i-1]+t[i-2]*t[i-3])%10;
     s=s+t[i];
     }

fprintf(g,"%d",s);

fclose(f);
fclose(g);
return 0;
}