#include<cstdio>
#include<cstring>
#include<algorithm>

char s[1000000];

int f(char x,char y){
	return (x!=y);
}

int main(){
	
	freopen("ordine.in","r",stdin);
	freopen("ordine.out","w",stdout);
	
	gets(s);
	
	int n = (int)strlen(s);
	
	std :: sort(s,s+n-1,f);
	
	printf("%s",s);
	
	return 0;
	
}