#include<bits/stdc++.h>
using namespace std;

int main()
{
    string str;

    while(cin>>str)
    {
        int len = str.length();
        for(int i = 0;i<len-1;i++)
        {
            for(int j = 0;j<len-i-1;j++)
            {
                if(str[j]>str[j+1])
                {
                    char temp = str[j];
                    str[j] = str[j+1];
                    str[j+1] = temp;  
                }
            }
        }
        cout<<str<<endl;
    }

    return 0;
}