The only difference between easy and hard versions is the length of the string. You can hack this problem only if you solve both problems.
Kirk has a binary string $s$ (a string which consists of zeroes and ones) of length $n$ and he is asking you to find a binary string $t$ of the same length which satisfies the following conditions:
- For any
$l$and$r$($1 \leq l \leq r \leq n$) the length of the longest non-decreasing subsequence of the substring$s_{l}s_{l+1} \ldots s_{r}$is equal to the length of the longest non-decreasing subsequence of the substring$t_{l}t_{l+1} \ldots t_{r}$; - The number of zeroes in
$t$is the maximum possible.
A non-decreasing subsequence of a string $p$ is a sequence of indices $i_1, i_2, \ldots, i_k$ such that $i_1 \lt i_2 \lt \ldots \lt i_k$ and $p_{i_1} \leq p_{i_2} \leq \ldots \leq p_{i_k}$. The length of the subsequence is $k$.
If there are multiple substrings which satisfy the conditions, output any.
Input
The first line contains a binary string of length not more than $2\: 000$.
Output
Output a binary string which satisfied the above conditions. If there are many such strings, output any of them.
Note
In the first example:
- For the substrings of the length
$1$the length of the longest non-decreasing subsequnce is$1$; - For
$l = 1, r = 2$the longest non-decreasing subsequnce of the substring$s_{1}s_{2}$is$11$and the longest non-decreasing subsequnce of the substring$t_{1}t_{2}$is$01$; - For
$l = 1, r = 3$the longest non-decreasing subsequnce of the substring$s_{1}s_{3}$is$11$and the longest non-decreasing subsequnce of the substring$t_{1}t_{3}$is$00$; - For
$l = 2, r = 3$the longest non-decreasing subsequnce of the substring$s_{2}s_{3}$is$1$and the longest non-decreasing subsequnce of the substring$t_{2}t_{3}$is$1$;
The second example is similar to the first one.
样例
110
010
010
010
0001111
0000000
0111001100111011101000
0011001100001011101000
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