1. 驼峰字符串

nums=str(input())
nums1=int(nums)

n=len(nums)
used=[False for _ in range(n)]
res=[]

def dfs(path,used,res):
    if len(path)==n:
        res.append(path[:])
        return
    for i in range(n):
        if not used[i]:
            
            used[i]=True
            path.append(nums[i])
            dfs(path,used,res)
            used[i]=False
            path.pop()

dfs([],used,res)
ans=[]
for i in range(len(res)):
    a=int(''.join(res[i]))
    if a<nums1:
        ans.append(a)
result=max(ans)
print(result)