def permut(mass):
    for i in range(0,len(mass)):
        if(i%2==0):
            mass[i]+=1000000
    mass.sort()
    for i in range(0,len(mass)):
        if(mass[i]>1000000):
             mass[i]-=1000000
    print(mass)


arr = [1,2,3,4,5] #Answers:
permut(arr) #[2, 4, 1, 3, 5]
arr = [1,2,3,4,5,6]
permut(arr) # [2, 4, 6, 1, 3, 5]
arr = [101, 50, 301, 450, 1001]
permut(arr) # [50, 450, 101, 301, 1001]