#include<fstream.h>
#include<string.h>
ifstream f("ordine.in");
ofstream g("ordine.out");
char a[10000],e,y;
int k,i,q;
char minim(int x,int &q)
{
char min=a[x+1];q=x+1;
for(int j=x+2;j<=k;j++)
	if(a[j]<min&&a[j]!=a[x])
	{min=a[i];q=i;}
return min;
}
int main()
{
f>>a;
k=strlen(a)-1;
y=a[0];q=0;
for(i=1;i<=k;i++)
	if(a[i]<y)
	{y=a[i];q=i;}
e=a[0];a[0]=y;a[q]=e;
for(i=1;i<=k;i++)
	{y=minim(i-1,q);
	 a[i]=a[q];
	 a[q]=y;
	}
int ga=1;
for(int j=k;j>=0&&ga;j--)
{ga=0;
 for(i=k;i>1;i--)
	 if(a[i-1]==a[i])
	 {e=a[i-1];a[i-1]=a[i-2];a[i-2]=e;ga=1;}
}
g<<a;
return 0;
}