Input TRS:
    1: and(true()) -> X
    2: if(true()) -> X
    3: if(false()) -> Y
    4: add(|0|()) -> X
    5: and(false()) -> false()
    6: add(s()) -> s()
    7: first(|0|(),X) -> nil()
    8: first(s(),cons()) -> cons()
    9: from() -> cons()
Extra variable in rule 2.
NO