var t,t1,t2,t3:longint;
s,n,i:int64;
f,g:text;
begin
assign(f,'koba.in');reset(f);
assign(g,'koba.out');rewrite(g);
read(f,n);
read(f,t1);
read(f,t2);
read(f,t3);
t1:=t1 mod 10;
t2:=t2 mod 10;
t3:=t3 mod 10;
s:=t1+t2+t3;
for i:=4 to n do
begin
t:=t3+t2*t1;
t:=t mod 10;
t1:=t2;
t2:=t3;
t3:=t;
s:=s+t;
end;
write(g,s);
close(f);
close(g);
end.