Input TRS:
    1: g(c(x,s(y))) -> g(c(s(x),y))
    2: f(c(s(x),y)) -> f(c(x,s(y)))
    3: f(f(x)) -> f(d(f(x)))
    4: f(x) -> x
Number of Rules: 4
Direct POLO(mPol) ... failed.