gnuplot ploting each series with different symbol

Question

I have a file with different series like:

x0_1 y0_1 A_0
x0_2 y0_2 B_0
...
x0_n y0_n N_0


x1_1 y1_1 A_1
x1_2 y1_2 B_1
...
x1_n y1_n N_1

If I