#include<cstdio>
#include<string>
#include<algorithm>
#include<vector>
using namespace std;
bool comp(char lhs,char rhs){
    return lhs < rhs;
}
int main(){
    char arr[201];
    scanf("%s",arr);
    string s = arr;
    vector<char> vec;
    int len = s.size();
    for(int i = 0 ; i < len;++i){
        vec.push_back(s[i]);
    }
    sort(vec.begin(),vec.end(),comp);
    for(int i = 0 ; i < len ;++i){
        printf("%c",vec[i]);
    }
    
}