Input TRS:
    1: a__f(f(a())) -> a__f(g(f(a())))
    2: mark(f(X)) -> a__f(X)
    3: mark(a()) -> a()
    4: mark(g(X)) -> g(mark(X))
    5: a__f(X) -> f(X)
Number of Rules: 5
Direct POLO(Sum) ... removes: 5 3 2
	I(mark) = x1 + 2
	I(a__f) = x1 + 1
	I(a) = 0
	I(f) = x1
	I(g) = x1
Number of Rules: 2
Direct POLO(Sum) ...Direct QLPOS ...Direct QKBOS ... failed.