Problem_339A.cpp

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

int main(int argc, char const *argv[])
{
    string s;
    cin>>s;
    string ans;
    vector<int> arr;
    if (s.length() == 1){
        cout<<s;
    }else{
        for (int i = 0; i < s.length(); i++)
        {   
            if(s[i] == '+') continue;
            if(s[i] == '1'){
                arr.push_back(1);
            }else if(s[i] == '2'){
                arr.push_back(2);
            }else{
                arr.push_back(3);
            }
        }
        sort(arr.begin(), arr.end());
        vector<int>::iterator ele;

        for(ele=arr.begin(); ele != arr.end(); ele++){
            cout<< *ele;
            if (ele != arr.end()-1)
                cout<<"+";
        }
    }
    
    return 0;
}