That works
In[2]:= Clear[a, b, c, d];
b = 1; a = 30;
{
If[b <= 2, Goto[10], Goto[20]];
Goto[20];
Label[10];
a = 10;
Print["a = " , a];
Goto[30];
Label[20];
a = 20;
Print["a = ", a];
Label[30];
Print["the end"]
}
During evaluation of In[2]:= a = 10
During evaluation of In[2]:= the end
Out[4]= {Null}
Do you see the difference? Hint: CompoundExpression and Goto.