CodeForces - 508B Anton and currency you all know

题目描述：

Berland, 2016. The exchange rate of currency you all know against the burle has increased so much that to simplify the calculations, its fractional part was neglected and the exchange rate is now assumed to be an integer.

Reliable sources have informed the financier Anton of some information about the exchange rate of currency you all know against the burle for tomorrow. Now Anton knows that tomorrow the exchange rate will be an even number, which can be obtained from the present rate by swapping exactly two distinct digits in it. Of all the possible values that meet these conditions, the exchange rate for tomorrow will be the maximum possible. It is guaranteed that today the exchange rate is an odd positive integer n. Help Anton to determine the exchange rate of currency you all know for tomorrow!

Input

The first line contains an odd positive integer n — the exchange rate of currency you all know for today. The length of number n's representation is within range from 2 to , inclusive. The representation of n doesn't contain any leading zeroes.

Output

If the information about tomorrow's exchange rate is inconsistent, that is, there is no integer that meets the condition, print  - 1.

Otherwise, print the exchange rate of currency you all know against the burle for tomorrow. This should be the maximum possible number of those that are even and that are obtained from today's exchange rate by swapping exactly two digits. Exchange rate representation should not contain leading zeroes.

Examples

Input

527

Output

572

Input

4573

Output

3574

Input

1357997531

Output

-1

题目大意：

给你一个数字，可以交换这个数字的两个位，得到一个最大的数字。

解题报告：

1：读题意可知，是最后一位数位和前面的数位交换，就有两种情况。

2：和大于它的数字交换就会变小，反之变大。要使最大，就要和最前面的比它小的偶数位交换。

3：如果没有，就找个离它最近的偶数位交换。再没有就是-1了。

代码：

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll N = 1e5+10;
char num[N];
int main(){
    scanf("%s", num);
    ll len = strlen(num);
    for(ll i=0; i<len-1; ++i){
        if(num[i] < num[len-1] && (num[i]-'0') % 2 == 0){
            swap(num[i], num[len-1]);
            printf("%s", num);
            return 0;
        }
    }
    for(ll i=len-2; i>=0; --i){
        if((num[i]-'0') % 2 == 0){
            swap(num[i], num[len-1]);
            printf("%s", num);
            return 0;
        }
    }
    printf("-1\n");
    return 0;
}