#include<bits/stdc++.h>
#define LL long long
#define LLL __int128
#define uint unsigned
#define ldb long double
#define uLL unsigned long long
using namespace std;
map<string,int>cnt;
signed main(){
    cin.tie(0)->sync_with_stdio(0);
    string s;cin>>s;
    for(auto c:s)++cnt[""s+c];
    while(cnt.size()>1){
        auto [_S,Sc]=*cnt.begin();auto S=_S;
        auto [_T,Tc]=*--cnt.end();auto T=_T;
        cnt.erase(cnt.begin()),cnt.erase(--cnt.end());
        int x=(Tc-1)/Sc,y=(x+1)*Sc-Tc;
        while(x--)S+=T;
        if(y)cnt[S]=y;if(Sc-y)cnt[S+T]=Sc-y;
    }
    auto [S,Sc]=*cnt.begin();
    while(Sc--)cout<<S;
    return 0;
}
/*
*/