#include <stdio.h>

int main(void) {
	int i, j, k, num[10] = {0};
	char n[100001], ans[100001];
	scanf("%s", n);
	i = 0;
	while(n[i] != '\0'){
		num[n[i] - '0']++;
		i++;
	}
	k = 0;
	for(i = 9;i >= 0;i--){
		for(j = 0;j < num[i];j++){
			ans[k] = '0' + i;
			k++;
		}
	}
	ans[k] = '\0';
	printf("%s\n", ans);

    return 0;
}