function andXorOr(A) {
    var stack = [A[0], A[1]];
    var S = A[0] ^ A[1];
    
    for(let i = 2; i < A.length; i++){
        while(stack.length > 0 && stack.slice(-1) >= A[i]){
            S = Math.max(S, stack.slice(-1) ^ A[i]);
            stack.pop();
        }
        if(stack.length > 0) S = Math.max(S, stack.slice(-1) ^ A[i]);
        stack.push(A[i])
    }
    return S;
}