def solve():
    X,Y,K,P=map(int,input().split())
    D=X-Y
    if K%2==1:
        if P==1:
            if D>=K:
                return True
            elif D<=-K:
                return False
            else:
                return D%2==0
        else:
            if D>=K:
                return False
            elif D<=-K:
                return True
            else:
                return D%2==0
    else:
        if P==1:
            if D>=K:
                return True
            elif D<=-K:
                return True
            else:
                return D%2==1
        else:
            if D>=K:
                return False
            elif D<=-K:
                return False
            else:
                return D%2==1
#==================================================
print("Alice" if solve() else "Bob")