var f,g:text;
    x,y,s,aux,i,j:longint;
begin
assign(f,'gropi.in');reset(f);
assign(g,'gropi.out');rewrite(g);
readln(f,x,y);
readln(f,x,y);
readln(f,i,j);
if y>j then begin
            aux:=y;
            y:=j;
            y:=aux;
            aux:=x;
            x:=i;
            i:=aux;
            end;
s:=(j-y+1)+1+(x-i)+1;
writeln(g,s);
close(g);
end.