%input labelauto;
beginfig(2);

u = 1cm;
ymax = 5;
xmax = 13;
xmin = ymin = -0.5;

path xx, yy;
xx = ((xmin,0) -- (xmax,0)) scaled u;

drawoptions(withpen pencircle scaled .7);
xx := xx scaled 1.05;
drawarrow xx;
drawoptions();

label.lrt (btex $x$ etex, point infinity of xx);

pair A, B, C, D, E, F, G, H, I, J, K, L, M;
A := (0cm,0);
B := (1cm,0);
C := (1.5cm,0);
D := (3cm,0);
E := (3.5cm,0);
F := (5.5cm,0);
G := (6cm,0);
H := (6.5cm,0);
I := (7cm,0);
J := (8cm,0);
K := (10cm,0);
L := (12cm,0);
M := (13cm,0);

draw A withpen pencircle scaled 3bp;
draw B withpen pencircle scaled 3bp;
draw C withpen pencircle scaled 3bp;
draw D withpen pencircle scaled 3bp;
draw E withpen pencircle scaled 3bp;
draw F withpen pencircle scaled 3bp;
draw G withpen pencircle scaled 3bp;
draw H withpen pencircle scaled 3bp;
draw I withpen pencircle scaled 3bp;
draw J withpen pencircle scaled 3bp;
draw K withpen pencircle scaled 3bp;
draw L withpen pencircle scaled 3bp;
draw M withpen pencircle scaled 3bp;

label.bot(btex $0$ etex, A);
label.bot(btex $\alpha_1$ etex, B);
label.bot(btex $\beta_1$ etex, C);
%label.bot(btex $\alpha_1+\beta_1$ etex, D);
label.top(btex $1.$ etex, D);
label.bot(btex ${1\over2}$ etex, E);
label.bot(btex $\alpha_2$ etex, F);
label.bot(btex $\beta_2$ etex, G);
label.top(btex $2.$ etex, H);
%label.bot(btex $\alpha_1+\beta_2$ etex, H);
label.bot(btex $1$ etex, I);
%label.bot(btex $\alpha_1+\beta_2$ etex, J);
label.top(btex $3.$ etex, J);
label.bot(btex $1{1\over2}$ etex, K);
%label.bot(btex $\alpha_2+\beta_2$ etex, L);
label.top(btex $4.$ etex, L);
label.bot(btex $2$ etex, M);

endfig;
end