class people:
    def __init__(self,hao,time):
        self.hao=hao
        self.time=time
n=int(input())
a=[int(i) for i in input().split()]
p=[people(i+1,a[i]) for i in range(n)]
p.sort(key=lambda x:x.time)
ans=0
for i in range(n):
    print(p[i].hao,end=' ')
    ans+=p[i].time*(n-i-1)
print()
print('%.2f'%(ans/n))

可以用结构体排序，也可以用二维列表来表示