#include<stdio.h>
int n,i,s=0;
int t[2000000];
int main ()
{

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

fscanf(f,"%d %d %d %d",&n,&t[1],&t[2],&t[3]);
s=s+t[1]%10+t[2]%10+t[3]%10;
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;
}