#include <bits/stdc++.h>   using namespace std;   int main() {     string s1;     while (cin >> s1) {       string s2 =   ;       for (int i = 0; i < s1.size(); i++) {         if (s1[i] !=  + ) s2 += s1[i];       }       sort(s2.begin(), s2.end());       for (int i = 0; i < s2.size(); i++) {         if (i) cout <<  + ;         cout << s2[i];       }       cout <<   n ;     }     return 0;   }   