0 QTRS
p(0) → 0 p(s(x)) → x le(0, y) → true le(s(x), 0) → false le(s(x), s(y)) → le(x, y) minus(x, 0) → x minus(x, s(y)) → if(le(x, s(y)), 0, p(minus(x, p(s(y))))) if(true, x, y) → x if(false, x, y) → y