NO

1 decompositions
 #0 -----------
   1: c() -> c()
   2: b() -> f(c())
   3: h(b(),h(a(),f(h(a(),f(f(f(b()))))))) -> h(a(),f(a()))
   4: b() -> h(b(),a())
   5: h(f(b()),c()) -> f(c())

unjoinable peak
    h(f(f(c())),c())
*<- h(f(b()),c()) ->*
    f(c())