Codeforces Round #539 (Div. 2) C Sasha and a Bit of Relax

题中意思显而易见，即求满足a_l⊕a_l+1⊕…⊕a_mid=a_mid+1⊕a_mid+2⊕…⊕a_{r且l到r的区间长为偶数的这样的数对(l,r)的个数。r且l}