arr=[]#输入的数组 for x in map(int,input().split()): arr.append(x) for i in range (len(arr)-1): for j in range (i,len(arr)): if arr[i]>arr[j]: t=arr[i] arr[i]=arr[j] arr[j]=t res=[] for i in range (0,20,2): res.append(arr[i]) for i in range (len(res)): if i==len(res)-1: print(res[i]) else : print(res[i],end=" ")