https://www.spoj.com/problems/ONP/
Using grammar
E -> (E + E) E -> (E - E) E -> (E * E) E -> (E / E) E -> (E ^ E) E -> letter
https://www.spoj.com/problems/ONP/
Using grammar
E -> (E + E) E -> (E - E) E -> (E * E) E -> (E / E) E -> (E ^ E) E -> letter