sub tree {
#        1         2         3
#2345678901234567890123456789012
($h,$f)=@_;@_=map$"x--$h.($_-1?0
x(2*$_-1):'*').$/,1..$h;s/0/rand   
>$f?'=':qw(0
@
*
+)[rand
4]/eg  
for@_;print@_