#include<map>
#include<set>
#include<ctime>
#include<cmath>
#include<queue>
#include<bitset>
#include<cstdio>
#include<vector>
#include<random>
#include<cstdlib>
#include<cstring>
#include<iostream>
#include<algorithm>
#define ll long long
using namespace std;
#define I ll
#define her1 20081214
#define IV void
#define cht 1000000007
#define ld double
#define Aestas16 392699
#define ull unsigned long long
#define cp(x,y)memcpy(x,y,sizeof y)
#define mem(x,val)memset(x,val,sizeof x)
#define D(i,j,n)for(register int i=j;i>=n;i--)
#define E(i,now)for(register int i=first[now],v=e[i].to;i;v=e[i=e[i].nxt].to)
#define F(i,j,n)for(register int i=j;i<=n;i++)
#define DL(i,j,n)for(register i64 i=j;i>=n;i--)
#define EL(i,now)for(register i64 i=first[now];i;i=e[i].nxt)
#define FL(i,j,n)for(register i64 i=j;i<=n;i++)
//#define D(i,j,n)for(int i=j;i>=n;i--)
//#define E(i,now)for(int i=first[now];i;i=e[i].nxt)
//#define F(i,j,n)for(int i=j;i<=n;i++)
//#define DL(i,j,n)for(register ll i=j;i>=n;i--)
//#define EL(i,now)for(register ll i=first[now];i;i=e[i].nxt)
//#define FL(i,j,n)for(register ll i=j;i<=n;i++)
ll read(){
	ll ans=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-')f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9')ans=ans*10+c-'0',c=getchar();
	return ans*f;
}
#undef ll
#include "assert.h"
mt19937_64 rnd(her1);
#include "functional"
using i64 = long long;
const int maxn = 1e6+5;

string sn[maxn];i64 tot;
i64 n,cnt[26];char s[maxn];
int main(){
	// freopen("1.in","r",stdin);
	// freopen("1.out","w",stdout);
	scanf("%s",s+1);n=strlen(s+1);
	F(i,1,n)cnt[s[i]-'a']++;i64 now=0;
	F(i,0,25)F(j,1,cnt[i])sn[++tot]=i+'a';
	F(_,0,20){
		i64 now=1;
		while(now<tot&&sn[now]==sn[now+1])now++;
		if(now==tot)break;
		i64 r=tot-now;
		i64 c=now%r;if(!c)c=r;
		// cout<<c<<' '<<r<<endl;
		F(i,c+1,c+r){
			i64 p=i;
			while(p+r<=tot)
				sn[i]+=sn[p+=r];
		}
		tot=now=c;i64 p=tot;
		D(i,c+r,c+1){
			if(i!=c+r&&sn[i]!=sn[i+1])now=p;
			sn[p]+=sn[i];if(p==1)p=now;else p--;
		}
	}
	F(i,1,tot)for(auto x:sn[i])putchar(x);

	return 0;
}