Let EXP be the class of all languages that are decidable in exponential time, i.e., in time O(2nk) for some constant k (where n is the input size). Formally, EXP=kNDTIME(2nk). It remains unknown whether NP=EXP, but it is known that PEXP. Prove that NP EXP. In other words, any efficiently verifiable language is decidable, in exponential time. Hint: For a specific verifier of an NP language, how many "effectively distinct" (to the verifier) certificates can there be?.