#include<stdio.h>
FILE*fin,*fout;
unsigned long int s,i,u1,u,u2,u3,upp,up,uppp,ucurent,t1,t2,t3,n;
int main(){
fin=fopen("koba.in","r");
fout=fopen("koba.out","w");
fscanf(fin,"%ld %ld %ld %ld",&n,&t1,&t2,&t3);
s=0;
uppp=t1%10; upp=t2%10;  up=t3%10; s=uppp+upp+up;s=s%10;
for(i=4;i<=n;i++){
ucurent=(up+upp*uppp)%10;
s=s+ucurent;
uppp=upp;upp=up;up=ucurent;


}
fprintf(fout,"%ld",s);
fclose(fin);
fclose(fout);
return 0;
}