def paixu(n):
    length=len(n)
    for i in range(length-1):
        for j in range(length-i-1):
            if n[j]<n[j+1]:
                n[j],n[j+1]=n[j+1],n[j]
    print(n)

n=[5,6,7,1,2,3]
paixu(n)